]> vaikene.ee Git - evaf/commitdiff
Added more tutorial sections.
authorEnar Väikene <enar@vaikene.net>
Fri, 23 Sep 2011 10:12:06 +0000 (13:12 +0300)
committerEnar Väikene <enar@vaikene.net>
Fri, 23 Sep 2011 10:12:06 +0000 (13:12 +0300)
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+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html lang="et" xmlns="http://www.w3.org/1999/xhtml" xml:lang="et">
+
+    <head>
+        <meta http-equiv="CONTENT-TYPE" content="text/html; charset=utf-8" />
+        <title>eVaf Tutorial - 06 - Storage Module</title>
+        <meta name="Author" content="Enar Väikene" />
+        <meta name="description" content="eVaf Tutorial" />
+        <meta name="keywords" content="evaf c++ application development framework tutorial password generator" />
+        <link rel="StyleSheet" href="evaf.css" type="text/css" media="all" />
+        <link rel="StyleSheet" href="highlight.css" type="text/css" media="all" />
+    </head>
+
+    <body>
+
+        <h1>eVaf Tutorial</h1>
+
+        <h2>06 - Storage Module</h2>
+
+        <p>In this section we start implementing the Storage module. The storage module stores non-sensitive data required to re-generate
+        passwords. We use a simple SQLITE database in this module, but nothing prevents us replacing it with a more complex storage
+        module in the future.</p>
+
+        <h3>iStorage interface</h3>
+
+        <p>Once again, we start by defining the interface for the module and create the file <tt>istorage.h</tt> in the
+        <tt>src/apps/PswGen/Storage</tt> directory:</p>
+
+        <pre class="hl"><span class="hl com">/**</span>
+<span class="hl com"> * &#64;file PswGen/Storage/istorage.h</span>
+<span class="hl com"> */</span>
+
+<span class="hl ppc">#ifndef __PSWGEN_STORAGE_ISTORAGE_H</span>
+<span class="hl ppc">#  define __PSWGEN_STORAGE_ISTORAGE_H</span>
+<span class="hl ppc">#endif</span> <span class="hl slc">// istorage.h</span></pre>
+
+        <p>Include Qt header files for <tt>QObject</tt> and <tt>QString</tt> as they are almost always needed. In additon, we are going to
+        include headers for <tt>QSharedData</tt> and <tt>QExplicitlySharedDataPointer</tt>. We need a container for the data that
+        we store and making it shared data object with the benefit of automatic reference counting and memory management makes sense.</p>
+
+        <pre class="hl"><span class="hl ppc">#include &lt;QObject&gt;</span>
+<span class="hl ppc">#include &lt;QString&gt;</span>
+<span class="hl ppc">#include &lt;QSharedData&gt;</span>
+<span class="hl ppc">#include &lt;QExplicitlySharedDataPointer&gt;</span></pre>
+
+        <p>Use the <tt>eVaf::PswGen</tt> namespace:</p>
+
+        <pre class="hl"><span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
+<span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
+
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span></pre>
+
+        <p>The container class for stored data has the following attributes:</p>
+        <ul>
+            <li>Name -- Name of the generated password</li>
+            <li>Length -- Length of the password</li>
+            <li>Options -- Additional parameters for the password generator</li>
+        </ul>
+
+        <p>The container class belongs to the Storage module and we use the <tt>eVaf::PswGen::Storage</tt> namespace for it:</p>
+
+        <pre class="hl"><span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
+
+<span class="hl kwc">class</span> Data <span class="hl opt">:</span> <span class="hl kwc">public</span> QSharedData
+<span class="hl opt">{</span>
+<span class="hl kwc">private</span><span class="hl opt">:</span>
+
+    <span class="hl kwb">bool</span> mModified<span class="hl opt">;</span>
+    QString mName<span class="hl opt">;</span>
+    <span class="hl kwb">int</span> mLength<span class="hl opt">;</span>
+    uint mFlags<span class="hl opt">;</span>
+
+<span class="hl opt">};</span>
+
+<span class="hl opt">}</span> <span class="hl slc">// eVaf::PswGen::Storage</span></pre>
+
+        <p>The extra attribute - <tt>mModified</tt> - is used to detect unsaved modifications in the data object.</p>
+
+        <p>Add constructors for the shared data class. Creating a data object without name makes no sense and we include the
+        name attribute in all our constructors:</p>
+
+        <pre class="hl"><span class="hl kwc">public</span><span class="hl opt">:</span>
+
+    <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span>
+        <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
+    <span class="hl opt">{}</span>
+
+    <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> <span class="hl kwb">int</span> l<span class="hl opt">,</span> uint f <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">)</span>
+        <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span>l<span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span>f<span class="hl opt">)</span>
+    <span class="hl opt">{}</span></pre>
+
+    <p>Fianlly, we add getter and setter methods:</p>
+
+    <pre class="hl">
+    QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> <span class="hl kwd">name</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mName<span class="hl opt">; }</span>
+
+    <span class="hl kwb">int</span> <span class="hl kwd">length</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mLength<span class="hl opt">; }</span>
+    <span class="hl kwb">void</span> <span class="hl kwd">setLength</span><span class="hl opt">(</span><span class="hl kwb">int</span> value<span class="hl opt">)</span>
+    <span class="hl opt">{</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(</span>mLength <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
+            mLength <span class="hl opt">=</span> value<span class="hl opt">;</span>
+            mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+
+    uint <span class="hl kwd">flags</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mFlags<span class="hl opt">; }</span>
+    <span class="hl kwb">void</span> <span class="hl kwd">setFlags</span><span class="hl opt">(</span>uint value<span class="hl opt">)</span>
+    <span class="hl opt">{</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(</span>mFlags <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
+            mFlags <span class="hl opt">=</span> value<span class="hl opt">;</span>
+            mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwb">bool</span> <span class="hl kwd">modified</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mModified<span class="hl opt">; }</span>
+
+    <span class="hl kwb">void</span> <span class="hl kwd">reset</span><span class="hl opt">() {</span> mModified <span class="hl opt">=</span> <span class="hl kwa">false</span><span class="hl opt">; }</span></pre>
+
+    <p>The <tt>reset()</tt> method resets the <tt>modified</tt> attribute.</p>
+
+    <p>Continue with the <tt>iStorage</tt> interface:</tt>
+
+    <pre class="hl"><span class="hl kwb">struct</span> iStorage
+<span class="hl opt">{</span>
+
+<span class="hl opt">};</span></pre>
+
+    <p>According to the specification, we need functions to store and query data:</p>
+
+    <pre class="hl">
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">) =</span> <span class="hl num">0</span><span class="hl opt">;</span>
+
+    <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">;</span></pre>
+
+    <p>The specification also mentions partial matches where entering "fa" would offer "facebook.com" if it exists. This could be done by
+    using the <tt>QCompleter</tt> class that provides auto completion in Qt widgets like <tt>QLineEdit</tt> and <tt>QComboBox</tt>. The
+    <tt>QCompleter<tt> class needs a <tt>QAbstractItemModel</tt> for the auto completion word list and we can provide it
+    from our <tt>Storage</tt> module:</tt>
+
+    <pre class="hl">
+    <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() =</span> <span class="hl num">0</span><span class="hl opt">;</span></pre>
+
+    <p><tt>QAbstractItemModel</tt> is not known at this moment and we need to add a forward class declaration to the beginning of the
+    <tt>istorage.h</tt> file:</p>
+
+    <pre class="hl">
+    <span class="hl kwc">class</span> QAbstractItemModel<span class="hl opt">;</span></pre>
+
+    <p>At the the end of the <tt>istorage.h</tt> file, we declare the <tt>iStorage</tt> interface:</p>
+
+    <pre class="hl"><span class="hl kwd">Q_DECLARE_INTERFACE</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">,</span> <span class="hl str">&quot;eVaf.PswGen.iStorage/1.0&quot;</span><span class="hl opt">)</span></pre>
+
+    <p>This is the complete <tt>istorage.h</tt> file:</p>
+
+    <pre class="hl"><span class="hl com">/**</span>
+<span class="hl com"> * &#64;file PswGen/Storage/istorage.h</span>
+<span class="hl com"> */</span>
+
+<span class="hl ppc">#ifndef __PSWGEN_STORAGE_ISTORAGE_H</span>
+<span class="hl ppc">#  define __PSWGEN_STORAGE_ISTORAGE_H</span>
+
+<span class="hl ppc">#include &lt;QObject&gt;</span>
+<span class="hl ppc">#include &lt;QString&gt;</span>
+<span class="hl ppc">#include &lt;QSharedData&gt;</span>
+<span class="hl ppc">#include &lt;QExplicitlySharedDataPointer&gt;</span>
+
+<span class="hl kwc">class</span> QAbstractItemModel<span class="hl opt">;</span>
+
+<span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
+<span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
+
+<span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
+
+<span class="hl com">/// Data stored for every password.</span>
+<span class="hl kwc">class</span> Data <span class="hl opt">:</span> <span class="hl kwc">public</span> QSharedData
+<span class="hl opt">{</span>
+<span class="hl kwc">public</span><span class="hl opt">:</span>
+
+    <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span>
+        <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
+    <span class="hl opt">{}</span>
+
+    <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> <span class="hl kwb">int</span> l<span class="hl opt">,</span> uint f <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">)</span>
+        <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span>l<span class="hl opt">)</span>
+        <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span>f<span class="hl opt">)</span>
+    <span class="hl opt">{}</span>
+
+    <span class="hl slc">/// Name of the password</span>
+    QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> <span class="hl kwd">name</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mName<span class="hl opt">; }</span>
+
+    <span class="hl slc">/// Length of the generated password</span>
+    <span class="hl kwb">int</span> <span class="hl kwd">length</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mLength<span class="hl opt">; }</span>
+    <span class="hl kwb">void</span> <span class="hl kwd">setLength</span><span class="hl opt">(</span><span class="hl kwb">int</span> value<span class="hl opt">)</span>
+    <span class="hl opt">{</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(</span>mLength <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
+            mLength <span class="hl opt">=</span> value<span class="hl opt">;</span>
+            mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl slc">/// Optional flags for the password generator</span>
+    uint <span class="hl kwd">flags</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mFlags<span class="hl opt">; }</span>
+    <span class="hl kwb">void</span> <span class="hl kwd">setFlags</span><span class="hl opt">(</span>uint value<span class="hl opt">)</span>
+    <span class="hl opt">{</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(</span>mFlags <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
+            mFlags <span class="hl opt">=</span> value<span class="hl opt">;</span>
+            mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl slc">/// Flag indicating that some fields are modified</span>
+    <span class="hl kwb">bool</span> <span class="hl kwd">modified</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mModified<span class="hl opt">; }</span>
+
+    <span class="hl slc">/// Resets the modified flag</span>
+    <span class="hl kwb">void</span> <span class="hl kwd">reset</span><span class="hl opt">() {</span> mModified <span class="hl opt">=</span> <span class="hl kwa">false</span><span class="hl opt">; }</span>
+
+<span class="hl kwc">private</span><span class="hl opt">:</span>
+
+    <span class="hl kwb">bool</span> mModified<span class="hl opt">;</span>
+    QString mName<span class="hl opt">;</span>
+    <span class="hl kwb">int</span> mLength<span class="hl opt">;</span>
+    uint mFlags<span class="hl opt">;</span>
+
+<span class="hl opt">};</span>
+
+<span class="hl opt">}</span> <span class="hl slc">// eVaf::PswGen::Storage</span>
+
+<span class="hl com">/// Password storage interface.</span>
+<span class="hl kwb">struct</span> iStorage
+<span class="hl opt">{</span>
+
+    <span class="hl com">/// Saves the data record</span>
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">) =</span> <span class="hl num">0</span><span class="hl opt">;</span>
+
+    <span class="hl com">/// Returns a data record by the name</span>
+    <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">;</span>
+
+    <span class="hl com">/// Returns an item model with the names of all the stored passwords</span>
+    <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() =</span> <span class="hl num">0</span><span class="hl opt">;</span>
+
+<span class="hl opt">};</span>
+
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span>
+
+<span class="hl kwd">Q_DECLARE_INTERFACE</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">,</span> <span class="hl str">&quot;eVaf.PswGen.iStorage/1.0&quot;</span><span class="hl opt">)</span>
+
+<span class="hl ppc">#endif</span> <span class="hl slc">// istorage.h</span><span class="hl ppc"></span></pre>
+
+    <p>We also create the <tt>iStorage</tt> file so that we can use <tt>#include &lt;Storage/iStorage&gt;</tt> in our other modules:</tt>
+
+    <pre class="hl"><span class="hl ppc">#include </span><span class="hl pps">&quot;istorage.h&quot;</span></pre>
+
+    <h3>Storage module</h3>
+
+    <p>The <tt>Storage<tt> module is simple enough to be derived directly from the <tt>Plugins::iPlugin</tt> interface and needs only one
+    header/source file. In general, I personally prefer short source files and follow the <i>one-class-per-file</i> rule. Only when classes
+    are very simple and closely related I put the into the same source file.</p>
+
+    <p>Create the <tt>module.h</tt> header file in the <tt>src/apps/PswGen/Storage</tt> directory. Include <tt>istorage.h</tt> and
+    <tt>Plugins/iPlugin</tt> header files. We use the <tt>eVaf::PswGen::Storage</tt> namespace for public classes and
+    <tt>eVaf::PswGen::Storage::Internal<tt> namespace for private classes.</p>
+
+    <pre class="hl"><span class="hl ppc">#ifndef __PSWGEN_STORAGE_MODULE_H</span>
+<span class="hl ppc">#  define __PSWGEN_STORAGE_MODULE_H</span>
+
+<span class="hl ppc">#include</span> <span class="hl pps">&quot;istorage.h&quot;</span><span class="hl ppc"></span>
+<span class="hl ppc">#include &lt;Plugins/iPlugin&gt;</span>
+
+<span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
+<span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
+
+<span class="hl slc">/// Module that stores options for strong passwords</span>
+<span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
+
+<span class="hl slc">/// Internal implementation of the Storage module</span>
+<span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
+
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span>
+<span class="hl ppc">#endif</span> <span class="hl slc">// module.h</span><span class="hl ppc"></span></pre>
+
+    <p>We use the same name <tt>Module</tt> for the class that implements the module. This class is public and goes to the
+    <tt>eVaf::PswGen::Storage</tt> namespace:</p>
+
+    <pre class="hl"><span class="hl kwc">class</span> Module <span class="hl opt">:</span> <span class="hl kwc">public</span> Plugins<span class="hl opt">::</span>iPlugin
+<span class="hl opt">{</span>
+    Q_OBJECT
+
+<span class="hl kwc">public</span><span class="hl opt">:</span>
+
+    <span class="hl kwd">Module</span><span class="hl opt">();</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">Module</span><span class="hl opt">();</span>
+
+<span class="hl opt">};</span></pre>
+
+    <p>Implement pure virtual methods in the <tt>iPlugin</tt> interface:</p>
+
+    <pre class="hl">
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> args<span class="hl opt">);</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">isReady</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mReady<span class="hl opt">; }</span></pre>
+
+    <p>This module needs more complex initialization that the <tt>Generator</tt> module and we use the <tt>mReady</tt> flag to
+    indicate that the module is fully initialized:</p>
+
+    <pre class="hl">
+<span class="hl kwc">private</span><span class="hl opt">:</span>
+
+    <span class="hl kwb">bool</span> mReady<span class="hl opt">;</span></pre>
+
+    <p>The <tt>StorageImpl</tt> class is the internal implementation of the <tt>iStorage</tt> interface:</p>
+
+    <pre class="hl">
+    Internal<span class="hl opt">::</span>StorageImpl <span class="hl opt">*</span> mStorage<span class="hl opt">;</span></pre>
+
+    <p>We could declare the <tt>Internal::StorageImpl</tt> class before the <tt>Module</tt> class, but as I like starting with more
+    generic (public) classes and then go into the details, we add a forward declaration to the beginning of the file:</p>
+
+    <pre class="hl">
+<span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
+    <span class="hl kwc">class</span> StorageImpl<span class="hl opt">;</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span></pre>
+
+    <p>The declaration of the <tt>StorageImpl</tt> class goes into the <tt>eVaf::PswGen::Storage::Internal</tt> namespace and the class
+    shall be derived both from <tt>QObject</tt> and <tt>iStorage</tt>. However, since we also need to implement the
+    <tt>QAbstractItemModel</tt> data model for the <tt>iStorage::autoCompletionModel()</tt> method, we derive it from the
+    <tt>QAbstractListModel</tt> class instead. We use the <tt>QAbstractListModel</tt> class because it meets our requirements
+    to return a list of auto completion words.</p>
+
+    <pre class="hl">
+<span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
+
+<span class="hl kwc">class</span> StorageImpl <span class="hl opt">:</span> <span class="hl kwc">public</span> QAbstractListModel<span class="hl opt">,</span> <span class="hl kwc">public</span> iStorage
+<span class="hl opt">{</span>
+    Q_OBJECT
+    <span class="hl kwd">Q_INTERFACES</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">)</span>
+
+<span class="hl kwc">public</span><span class="hl opt">:</span>
+
+    <span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
+
+<span class="hl opt">};</span>
+
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span></pre>
+
+    <p>First, we implement pure virtual methods found in the <tt>iStorage</tt> interface:</p>
+
+    <pre class="hl">
+    <span class="hl com">/*</span>
+        <span class="hl com">iStorage interface</span>
+    <span class="hl com">*/</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">);</span>
+
+    <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span>
+
+    <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() {</span> <span class="hl kwa">return this</span><span class="hl opt">; }</span></pre>
+
+    <p>Since the <tt>QAbstractItemModel</tt> data model is implemented by the same class, we can simply return <tt>this</tt> in the
+    <tt>autoCompletionModel()</tt> model.</p>
+
+    <p>The <tt>QAbstractListModel</tt> class also has pure virtual methods that need to be implemented:</p>
+
+    <pre class="hl">
+    <span class="hl com">/*</span>
+        <span class="hl com">QAbstractListModel methods</span>
+    <span class="hl com">*/</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">int</span> <span class="hl kwd">rowCount</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> parent<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mData<span class="hl opt">.</span><span class="hl kwd">count</span><span class="hl opt">(); }</span>
+
+    <span class="hl kwc">virtual</span> QVariant <span class="hl kwd">data</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> index<span class="hl opt">,</span> <span class="hl kwb">int</span> role <span class="hl opt">=</span> Qt<span class="hl opt">::</span>DisplayRole<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span></pre>
+
+    <p><tt>mData</tt> here is a container with all the stored data objects, which we add to the <tt>private</tt> section. We use
+    a <tt>QMap&lt;QString, QExplicitlySharedDataPointer&lt;Storage::Data&gt; &gt;</tt> for this purpose as it allows fast lookups
+    by the name string.</p>
+
+    <pre class="hl">
+<span class="hl kwc">private</span><span class="hl opt">:</span>
+
+    QMap<span class="hl opt">&lt;</span>QString<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt; &gt;</span> mData<span class="hl opt">;</span></pre>
+
+    <p>Permanent data storage is done using a SQLITE database. We add the database object and a methods to load data from the database. We
+    also need a method to create database tables if they do not exist yet:</p>
+
+    <pre class="hl">
+    QSqlDatabase mDb<span class="hl opt">;</span>
+
+    <span class="hl kwb">bool</span> <span class="hl kwd">createTables</span><span class="hl opt">();</span>
+
+    <span class="hl kwb">bool</span> <span class="hl kwd">loadData</span><span class="hl opt">();</span></pre>
+
+    <p>The database object needs names for the connection and for the database, which we can add as constants to the class:</p>
+
+    <pre class="hl">
+    <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbConnectionName<span class="hl opt">;</span>
+
+    <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbName<span class="hl opt">;</span></pre>
+
+    <p>The database needs to be opened and closed, and the list of data objects populated with data from the database. For this purpose
+    we add <tt>init()</tt> and <tt>done()</tt> methods to the public section of the class. The <tt>init()</tt> method can return
+    <tt>false</tt> if the initialization fails.</p>
+
+    <pre class="hl">
+    <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">();</span>
+
+    <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span></pre>
+
+    <p>This is the final <tt>module.h</tt> file:</p>
+
+<pre class="hl"><span class="hl com">/**</span>
+<span class="hl com"> * &#64;file PswGen/Storage/module.h</span>
+<span class="hl com"> */</span>
+
+<span class="hl ppc">#ifndef __PSWGEN_STORAGE_MODULE_H</span>
+<span class="hl ppc">#  define __PSWGEN_STORAGE_MODULE_H</span>
+
+<span class="hl ppc">#include</span> <span class="hl pps">&quot;istorage.h&quot;</span><span class="hl ppc"></span>
+
+<span class="hl ppc">#include &lt;Plugins/iPlugin&gt;</span>
+
+<span class="hl ppc">#include &lt;QObject&gt;</span>
+<span class="hl ppc">#include &lt;QString&gt;</span>
+<span class="hl ppc">#include &lt;QAbstractListModel&gt;</span>
+<span class="hl ppc">#include &lt;QMap&gt;</span>
+<span class="hl ppc">#include &lt;QtSql/QSqlDatabase&gt;</span>
+
+
+<span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
+<span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
+
+<span class="hl slc">/// Module that stores options for strong passwords</span>
+<span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
+
+<span class="hl slc">/// Internal implementation of the Storage module</span>
+<span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
+    <span class="hl kwc">class</span> StorageImpl<span class="hl opt">;</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span>
+
+<span class="hl com">/// Module implementing the iStorage interface.</span>
+<span class="hl kwc">class</span> Module <span class="hl opt">:</span> <span class="hl kwc">public</span> Plugins<span class="hl opt">::</span>iPlugin
+<span class="hl opt">{</span>
+    Q_OBJECT
+
+<span class="hl kwc">public</span><span class="hl opt">:</span>
+
+    <span class="hl kwd">Module</span><span class="hl opt">();</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">Module</span><span class="hl opt">();</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> args<span class="hl opt">);</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">isReady</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mReady<span class="hl opt">; }</span>
+
+
+<span class="hl kwc">private</span><span class="hl opt">:</span> <span class="hl slc">// Members</span>
+
+    <span class="hl slc">/// Flag indicating that the module is ready</span>
+    <span class="hl kwb">bool</span> mReady<span class="hl opt">;</span>
+
+    <span class="hl slc">/// iStorage interface instance</span>
+    Internal<span class="hl opt">::</span>StorageImpl <span class="hl opt">*</span> mStorage<span class="hl opt">;</span>
+
+<span class="hl opt">};</span>
+
+<span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
+
+<span class="hl com">/// iStorage interface implementation.</span>
+<span class="hl kwc">class</span> StorageImpl <span class="hl opt">:</span> <span class="hl kwc">public</span> QAbstractListModel<span class="hl opt">,</span> <span class="hl kwc">public</span> iStorage
+<span class="hl opt">{</span>
+    Q_OBJECT
+    <span class="hl kwd">Q_INTERFACES</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">)</span>
+
+<span class="hl kwc">public</span><span class="hl opt">:</span>
+
+    <span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
+
+    <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">();</span>
+
+    <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span>
+
+    <span class="hl com">/*</span>
+        <span class="hl com">iStorage interface</span>
+    <span class="hl com">*/</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">);</span>
+
+    <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span>
+
+    <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() {</span> <span class="hl kwa">return this</span><span class="hl opt">; }</span>
+
+    <span class="hl com">/*</span>
+        <span class="hl com">QAbstractListModel methods</span>
+    <span class="hl com">*/</span>
+
+    <span class="hl kwc">virtual</span> <span class="hl kwb">int</span> <span class="hl kwd">rowCount</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> parent<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mData<span class="hl opt">.</span><span class="hl kwd">count</span><span class="hl opt">(); }</span>
+
+    <span class="hl kwc">virtual</span> QVariant <span class="hl kwd">data</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> index<span class="hl opt">,</span> <span class="hl kwb">int</span> role <span class="hl opt">=</span> Qt<span class="hl opt">::</span>DisplayRole<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span>
+
+<span class="hl kwc">private</span><span class="hl opt">:</span> <span class="hl slc">// Members</span>
+
+    <span class="hl slc">/// Name of the database connection</span>
+    <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbConnectionName<span class="hl opt">;</span>
+
+    <span class="hl slc">/// Name of the database file without path</span>
+    <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbName<span class="hl opt">;</span>
+
+    <span class="hl slc">/// Database connection</span>
+    QSqlDatabase mDb<span class="hl opt">;</span>
+
+    <span class="hl slc">/// List of name/data pairs</span>
+    QMap<span class="hl opt">&lt;</span>QString<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt; &gt;</span> mData<span class="hl opt">;</span>
+
+
+<span class="hl kwc">private</span><span class="hl opt">:</span> <span class="hl slc">// Methods</span>
+
+    <span class="hl com">/// Creates database tables if necessary</span>
+    <span class="hl kwb">bool</span> <span class="hl kwd">createTables</span><span class="hl opt">();</span>
+
+    <span class="hl com">/// Loads data from the database</span>
+    <span class="hl kwb">bool</span> <span class="hl kwd">loadData</span><span class="hl opt">();</span>
+
+<span class="hl opt">};</span>
+
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
+<span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span>
+
+<span class="hl ppc">#endif</span> <span class="hl slc">// module.h</span><span class="hl ppc"></span></pre>
+
+    <p>Continue implementing the <a href="pswgen07.html">Storage Module</a>.</p>
+
+    </body>
+</html>
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+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html lang="et" xmlns="http://www.w3.org/1999/xhtml" xml:lang="et">
+
+    <head>
+        <meta http-equiv="CONTENT-TYPE" content="text/html; charset=utf-8" />
+        <title>eVaf Tutorial - 07 - Storage Module</title>
+        <meta name="Author" content="Enar Väikene" />
+        <meta name="description" content="eVaf Tutorial" />
+        <meta name="keywords" content="evaf c++ application development framework tutorial password generator" />
+        <link rel="StyleSheet" href="evaf.css" type="text/css" media="all" />
+        <link rel="StyleSheet" href="highlight.css" type="text/css" media="all" />
+    </head>
+
+    <body>
+
+        <h1>eVaf Tutorial</h1>
+
+        <h2>07 - Storage Module</h2>
+
+        <p>Create the <tt>module.cpp</tt> file in the <tt>src/apps/PswGen/Storage</tt> directory:</tt>
+
+        <pre class="hl"><span class="hl com">/**</span>
+<span class="hl com"> * &#64;file PswGen/Storage/module.cpp</span>
+<span class="hl com"> */</span>
+
+<span class="hl ppc">#include</span> <span class="hl pps">&quot;module.h&quot;</span><span class="hl ppc"></span>
+<span class="hl ppc">#include &lt;QtCore&gt;</span></pre>
+
+        <p>Copy version information files from the <tt>Generator<tt> module:</p>
+
+        <pre>evaf/src/apps/PswGen/Storage $ <code>cp ../Generator/version.{h,rc} .</code></pre>
+
+        <p>Modify the <tt>version.h</tt> file:</p>
+
+        <pre class="hl"><span class="hl com">/**</span>
+<span class="hl com"> * &#64;file PswGen/Storage/version.h</span>
+<span class="hl com"> */</span>
+
+<span class="hl ppc">#ifndef __PSWGEN_STORAGE_VERSION_H</span>
+<span class="hl ppc">#define   __PSWGEN_STORAGE_VERSION_H</span>
+
+<span class="hl ppc">#include &lt;version_rc.h&gt;</span>
+
+<span class="hl com">/**</span>
+<span class="hl com"> * Module/library version number in the form major,minor,release,build</span>
+<span class="hl com"> */</span>
+<span class="hl ppc">#define VER_FILE_VERSION                0,1,1,1</span>
+
+<span class="hl com">/**</span>
+<span class="hl com"> * Module/library version number in the string format (shall end with \0)</span>
+<span class="hl com"> */</span>
+<span class="hl ppc">#define VER_FILE_VERSION_STR</span>            <span class="hl pps">&quot;0.1.1.1\0&quot;</span><span class="hl ppc"></span>
+
+<span class="hl com">/**</span>
+<span class="hl com"> * Module/library name (shall end with \0)</span>
+<span class="hl com"> */</span>
+<span class="hl ppc">#define VER_MODULE_NAME_STR</span>             <span class="hl pps">&quot;PswStorage\0&quot;</span><span class="hl ppc"></span>
+
+<span class="hl com">/**</span>
+<span class="hl com"> * Module type (see version_rc.h for all the types)</span>
+<span class="hl com"> */</span>
+<span class="hl ppc">#define VER_MODULE_TYPE                 MT_GENERIC</span>
+
+<span class="hl com">/**</span>
+<span class="hl com"> * Module type in the string format (see version_rc for all the types)</span>
+<span class="hl com"> */</span>
+<span class="hl ppc">#define VER_MODULE_TYPE_STR             MT_GENERIC</span>
+
+<span class="hl com">/**</span>
+<span class="hl com"> * Original file name for windows (shall end with \0)</span>
+<span class="hl com"> */</span>
+<span class="hl ppc">#define VER_ORIGINAL_FILE_NAME_STR</span>      <span class="hl pps">&quot;PswStorage.dll\0&quot;</span><span class="hl ppc"></span>
+
+<span class="hl com">/**</span>
+<span class="hl com"> * Description of the module/library (shall end with \0)</span>
+<span class="hl com"> */</span>
+<span class="hl ppc">#define VER_FILE_DESCRIPTION_STR</span>         <span class="hl pps">&quot;Module that stores data for generating strong passwords.\0&quot;</span><span class="hl ppc"></span>
+
+<span class="hl ppc">#endif</span> <span class="hl slc">// version.h</span><span class="hl ppc"></span></pre>
+
+        <p>Include the <tt>version.h</tt> header file in <tt>module.cpp</tt> and export version information:</p>
+
+        <pre class="hl">
+<span class="hl ppc">#include</span> <span class="hl pps">&quot;version.h&quot;</span><span class="hl ppc"></span>
+
+<span class="hl kwd">VER_EXPORT_VERSION_INFO</span><span class="hl opt">()</span></pre>
+
+        <p>Make it a proper Qt plugin by using the <tt>Q_EXPORT_PLUGIN2()</tt> macro:</p>
+
+        <pre class="hl"><span class="hl kwd">Q_EXPORT_PLUGIN2</span><span class="hl opt">(</span>VER_MODULE_NAME_STR<span class="hl opt">,</span> eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>Storage<span class="hl opt">::</span>Module<span class="hl opt">)</span></pre>
+
+        <p>The <tt>Module</tt> class creates the internal <tt>StorageImpl</tt> object in the constructor, but initializes it in the
+        <tt>init()</tt> method. This way we can return errors from the module if initialization fails. Similarly, we finalize the
+        internal <tt>StorageImpl</tt> object in the <tt>done()</tt> method and delete in the destructor.</p>
+
+        <p>The module is ready when the internal <tt>StorageImpl</tt> object is initalized and we set the <tt>mReady</tt> flag to
+        <tt>true</tt> when the initialization is done and back to <tt>false</tt> in the <tt>done()</tt> method.</p>
+
+        <p>The rest of the code sets the name of the object and outputs info messages.</p>
+
+        <pre class="hl">Module<span class="hl opt">::</span><span class="hl kwd">Module</span><span class="hl opt">()</span>
+    <span class="hl opt">:</span> Plugins<span class="hl opt">::</span><span class="hl kwd">iPlugin</span><span class="hl opt">()</span>
+    <span class="hl opt">,</span> <span class="hl kwd">mReady</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">setObjectName</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;%1.%2&quot;</span><span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>VER_MODULE_NAME_STR<span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>__FUNCTION__<span class="hl opt">));</span>
+
+    mStorage <span class="hl opt">=</span> <span class="hl kwa">new</span> Internal<span class="hl opt">::</span>StorageImpl<span class="hl opt">;</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s created&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+Module<span class="hl opt">::~</span><span class="hl kwd">Module</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl kwa">delete</span> mStorage<span class="hl opt">;</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s destroyed&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">bool</span> Module<span class="hl opt">::</span><span class="hl kwd">init</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> args<span class="hl opt">)</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">Q_UNUSED</span><span class="hl opt">(</span>args<span class="hl opt">);</span>
+
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>mStorage<span class="hl opt">-&gt;</span><span class="hl kwd">init</span><span class="hl opt">())</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+
+    mReady <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s initialized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">void</span> Module<span class="hl opt">::</span><span class="hl kwd">done</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    mReady <span class="hl opt">=</span> <span class="hl kwa">false</span><span class="hl opt">;</span>
+
+    mStorage<span class="hl opt">-&gt;</span><span class="hl kwd">done</span><span class="hl opt">();</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s finalized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span></pre>
+
+        <p>The <tt>StorageImpl</tt> class does very little in the constructor and in the destructor:</p>
+
+        <pre class="hl">StorageImpl<span class="hl opt">::</span><span class="hl kwd">StorageImpl</span><span class="hl opt">()</span>
+    <span class="hl opt">:</span> <span class="hl kwd">QAbstractListModel</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">setObjectName</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;%1.iGenerator&quot;</span><span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>VER_MODULE_NAME_STR<span class="hl opt">));</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s created&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+StorageImpl<span class="hl opt">::~</span><span class="hl kwd">StorageImpl</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s destroyed&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span></pre>
+
+        <p>Initialization of the <tt>StorageImpl</tt> class happens in the <tt>init()</tt> method, where we open the database connection,
+        create tables if necessary and load data from the database. We also register the <tt>iStorage</tt> interface in the global
+        registry of interfaces.</p>
+
+        <p>We use the <tt>Common::iApp</tt> interface to find the data root directory where the SQLITE database file is going to be
+        located.</p>
+
+        <pre class="hl"><span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">init</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl slc">// Open the database</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>QSqlDatabase<span class="hl opt">::</span><span class="hl kwd">contains</span><span class="hl opt">(</span>DbConnectionName<span class="hl opt">)) {</span>
+        <span class="hl slc">// No database connection yet</span>
+        mDb <span class="hl opt">=</span> QSqlDatabase<span class="hl opt">::</span><span class="hl kwd">addDatabase</span><span class="hl opt">(</span><span class="hl str">&quot;QSQLITE&quot;</span><span class="hl opt">,</span> DbConnectionName<span class="hl opt">);</span>
+        mDb<span class="hl opt">.</span><span class="hl kwd">setDatabaseName</span><span class="hl opt">(</span>Common<span class="hl opt">::</span>iApp<span class="hl opt">::</span><span class="hl kwd">instance</span><span class="hl opt">()-&gt;</span><span class="hl kwd">dataRootDir</span><span class="hl opt">() +</span> DbName<span class="hl opt">);</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(!</span>mDb<span class="hl opt">.</span><span class="hl kwd">open</span><span class="hl opt">()) {</span>
+            QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+            <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to open database : %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+            <span class="hl kwa">return false</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+    <span class="hl kwa">else</span> <span class="hl opt">{</span>
+        <span class="hl slc">// Database connection already exists</span>
+        mDb <span class="hl opt">=</span> QSqlDatabase<span class="hl opt">::</span><span class="hl kwd">database</span><span class="hl opt">(</span>DbConnectionName<span class="hl opt">);</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl slc">// Create tables if necessary</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span><span class="hl kwd">createTables</span><span class="hl opt">())</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+
+    <span class="hl slc">// Load data</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span><span class="hl kwd">loadData</span><span class="hl opt">())</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+
+    <span class="hl slc">/// Register our interface</span>
+    Common<span class="hl opt">::</span>iRegistry<span class="hl opt">::</span><span class="hl kwd">instance</span><span class="hl opt">()-&gt;</span><span class="hl kwd">registerInterface</span><span class="hl opt">(</span><span class="hl str">&quot;iStorage&quot;</span><span class="hl opt">,</span> <span class="hl kwa">this</span><span class="hl opt">);</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s initialized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span></pre>
+
+        <p>The finalization of the <tt>StorageImpl</tt> class happens in the <tt>done()</tt> method, where we only need to clear the list
+        of shared data objects:</p>
+
+        <pre class="hl"><span class="hl kwb">void</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">done</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    mData<span class="hl opt">.</span><span class="hl kwd">clear</span><span class="hl opt">();</span>
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s finalized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span></pre>
+
+        <p>The <tt>StorageImpl::save()</tt> method verifies that the shared data object is valid and the name not empty. Then it either
+        adds a new data record to the database or updates an existing one.</p>
+
+        <pre class="hl"><span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">)</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">EVAF_TEST_X</span><span class="hl opt">(</span>data<span class="hl opt">,</span> <span class="hl str">&quot;Data cannot be null&quot;</span><span class="hl opt">);</span>
+    <span class="hl kwd">EVAF_TEST_X</span><span class="hl opt">(!</span>name<span class="hl opt">.</span><span class="hl kwd">isEmpty</span><span class="hl opt">(),</span> <span class="hl str">&quot;Name cannot be empty&quot;</span><span class="hl opt">);</span>
+
+    <span class="hl slc">// Is it an update or a new data record?</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>mData<span class="hl opt">.</span><span class="hl kwd">constFind</span><span class="hl opt">(</span>name<span class="hl opt">) !=</span> mData<span class="hl opt">.</span><span class="hl kwd">constEnd</span><span class="hl opt">()) {</span>
+        <span class="hl slc">// This is an update</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">modified</span><span class="hl opt">()) {</span>
+            QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+            <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;UPDATE data SET length =</span> <span class="hl esc">\'</span><span class="hl str">%1</span><span class="hl esc">\'</span><span class="hl str">, flags =</span> <span class="hl esc">\'</span><span class="hl str">%2</span><span class="hl esc">\'</span> <span class="hl str">WHERE name =</span> <span class="hl esc">\'</span><span class="hl str">%3</span><span class="hl esc">\'</span><span class="hl str">;&quot;</span><span class="hl opt">)</span>
+                            <span class="hl opt">.</span><span class="hl kwd">arg</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">length</span><span class="hl opt">()).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">flags</span><span class="hl opt">()).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>name<span class="hl opt">))) {</span>
+                QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+                <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to update</span> <span class="hl esc">\'</span><span class="hl str">%s</span><span class="hl esc">\'</span> <span class="hl str">: %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>name<span class="hl opt">),</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+                <span class="hl kwa">return false</span><span class="hl opt">;</span>
+            <span class="hl opt">}</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+    <span class="hl kwa">else</span> <span class="hl opt">{</span>
+        <span class="hl slc">// Store to the database</span>
+        QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;INSERT INTO data (name, length, flags) VALUES (</span><span class="hl esc">\'</span><span class="hl str">%1</span><span class="hl esc">\'</span><span class="hl str">, %2, %3);&quot;</span><span class="hl opt">)</span>
+                            <span class="hl opt">.</span><span class="hl kwd">arg</span><span class="hl opt">(</span>name<span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">length</span><span class="hl opt">())</span>
+                            <span class="hl opt">.</span><span class="hl kwd">arg</span><span class="hl opt">(</span><span class="hl kwb">int</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">flags</span><span class="hl opt">())))) {</span>
+            QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+            <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to insert</span> <span class="hl esc">\'</span><span class="hl str">%s</span><span class="hl esc">\'</span> <span class="hl str">: %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>name<span class="hl opt">),</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+            <span class="hl kwa">return false</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+
+        <span class="hl slc">// Store also into the local hash</span>
+        mData<span class="hl opt">.</span><span class="hl kwd">insert</span><span class="hl opt">(</span>name<span class="hl opt">,</span> data<span class="hl opt">);</span>
+
+        <span class="hl slc">// Reset the model</span>
+        <span class="hl kwd">reset</span><span class="hl opt">();</span>
+    <span class="hl opt">}</span>
+
+    data<span class="hl opt">-&gt;</span><span class="hl kwd">reset</span><span class="hl opt">();</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span></pre>
+
+        <p>Calling the <tt>reset()</tt> method resets the <tt>QAbstractItemModel</tt> data model and assures that the associated widget
+        updates the <tt>QCompleter</tt> with a fresh list of auto completion words. Resetting the data model in this case is fine as
+        long as the data model is simple and the list short. The proper way would be finding out the actual insertion point and using
+        <tt>beginInsertRows()</tt> and <tt>endInsertRows()</tt> methods.</p>
+
+        <p>Querying data is much simpler thanks to the internal <tt>QMap</tt> container:</p>
+
+        <pre class="hl">QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span>
+<span class="hl opt">{</span>
+    QMap<span class="hl opt">&lt;</span>QString<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt; &gt;::</span>const_iterator it <span class="hl opt">=</span> mData<span class="hl opt">.</span><span class="hl kwd">constFind</span><span class="hl opt">(</span>name<span class="hl opt">);</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>it <span class="hl opt">!=</span> mData<span class="hl opt">.</span><span class="hl kwd">constEnd</span><span class="hl opt">())</span>
+        <span class="hl kwa">return</span> it<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">();</span>
+    <span class="hl kwa">else</span>
+        <span class="hl kwa">return</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;();</span>
+<span class="hl opt">}</span></pre>
+
+        <p>We return an empty <tt>QExplicitlySharedDataPointer</tt> object if no data objects with the given name exists.</p>
+
+        <p>The <tt>data()</tt> method returns names of data objects for the <tt>QCompleter</tt> auto completion list of words:</p>
+
+        <pre class="hl">QVariant StorageImpl<span class="hl opt">::</span><span class="hl kwd">data</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> index<span class="hl opt">,</span> <span class="hl kwb">int</span> role<span class="hl opt">)</span> <span class="hl kwb">const</span>
+<span class="hl opt">{</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>index<span class="hl opt">.</span><span class="hl kwd">isValid</span><span class="hl opt">() ||</span> index<span class="hl opt">.</span><span class="hl kwd">row</span><span class="hl opt">() &lt;</span> <span class="hl num">0</span> <span class="hl opt">||</span> index<span class="hl opt">.</span><span class="hl kwd">row</span><span class="hl opt">() &gt;=</span> mData<span class="hl opt">.</span><span class="hl kwd">size</span><span class="hl opt">() ||</span> index<span class="hl opt">.</span><span class="hl kwd">column</span><span class="hl opt">() !=</span> <span class="hl num">0</span><span class="hl opt">)</span>
+        <span class="hl kwa">return</span> <span class="hl kwd">QVariant</span><span class="hl opt">();</span>
+
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>role <span class="hl opt">==</span> Qt<span class="hl opt">::</span>EditRole <span class="hl opt">||</span> role <span class="hl opt">==</span> Qt<span class="hl opt">::</span>DisplayRole<span class="hl opt">)</span>
+        <span class="hl kwa">return</span> mData<span class="hl opt">.</span><span class="hl kwd">keys</span><span class="hl opt">().</span><span class="hl kwd">at</span><span class="hl opt">(</span>index<span class="hl opt">.</span><span class="hl kwd">row</span><span class="hl opt">());</span>
+
+    <span class="hl kwa">return</span> <span class="hl kwd">QVariant</span><span class="hl opt">();</span>
+<span class="hl opt">}</span></pre>
+
+        <p>The <tt>createTabled()</tt> method creates the <tt>data</tt> table if it does not exist. This function could be improved to
+        alter the <tt>data</tt> table if it exists, but is from an older version. Right now we assume that if the table exists, it
+        is good for our application:</p>
+
+        <pre class="hl"><span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">createTables</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl str">&quot;SELECT name FROM sqlite_master WHERE type=</span><span class="hl esc">\'</span><span class="hl str">table</span><span class="hl esc">\'</span> <span class="hl str">AND name=</span><span class="hl esc">\'</span><span class="hl str">data</span><span class="hl esc">\'</span><span class="hl str">;&quot;</span><span class="hl opt">)) {</span>
+        QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+        <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to query database : %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>q<span class="hl opt">.</span><span class="hl kwd">isActive</span><span class="hl opt">() &amp;&amp;</span> q<span class="hl opt">.</span><span class="hl kwd">isSelect</span><span class="hl opt">() &amp;&amp;</span> q<span class="hl opt">.</span><span class="hl kwd">first</span><span class="hl opt">())</span>
+        <span class="hl kwa">return true</span><span class="hl opt">;</span> <span class="hl slc">// We already have a table called 'data'</span>
+
+    <span class="hl slc">// Create the 'data' table</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl str">&quot;CREATE TABLE data (name text primary key not null, length integer, flags integer);&quot;</span><span class="hl opt">)) {</span>
+        QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+        <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to create table</span> <span class="hl esc">\'</span><span class="hl str">data</span><span class="hl esc">\'</span> <span class="hl str">: %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span></pre>
+
+        <p>Finally, the <tt>loadData()</tt> method loads all the data records from the database to the memory:</p>
+
+        <pre class="hl"><span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">loadData</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl str">&quot;SELECT name, length, flags FROM data;&quot;</span><span class="hl opt">)) {</span>
+        QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+        <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to query database : %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwa">while</span> <span class="hl opt">(</span>q<span class="hl opt">.</span><span class="hl kwd">next</span><span class="hl opt">()) {</span>
+        QString name <span class="hl opt">=</span> q<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">).</span><span class="hl kwd">toString</span><span class="hl opt">();</span>
+        QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">data</span><span class="hl opt">(</span><span class="hl kwa">new</span> Storage<span class="hl opt">::</span><span class="hl kwd">Data</span><span class="hl opt">(</span>name<span class="hl opt">,</span> q<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">(</span><span class="hl num">1</span><span class="hl opt">).</span><span class="hl kwd">toInt</span><span class="hl opt">(),</span> <span class="hl kwd">uint</span><span class="hl opt">(</span>q<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">(</span><span class="hl num">2</span><span class="hl opt">).</span><span class="hl kwd">toInt</span><span class="hl opt">())));</span>
+        mData<span class="hl opt">.</span><span class="hl kwd">insert</span><span class="hl opt">(</span>name<span class="hl opt">,</span> data<span class="hl opt">);</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwd">reset</span><span class="hl opt">();</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span></pre>
+
+        <p>Resetting the <tt>QAbstractItemModel</tt> data model here is ok, becase before loading any data the model is supposed to be
+        empty.</p>
+
+        <p>Here is the complete <tt>module.cpp</tt> file:
+
+        <pre class="hl"><span class="hl com">/**</span>
+<span class="hl com"> * &#64;file PswGen/Storage/module.cpp</span>
+<span class="hl com"> */</span>
+
+<span class="hl ppc">#include</span> <span class="hl pps">&quot;module.h&quot;</span><span class="hl ppc"></span>
+<span class="hl ppc">#include</span> <span class="hl pps">&quot;version.h&quot;</span><span class="hl ppc"></span>
+
+<span class="hl ppc">#include &lt;Common/Globals&gt;</span>
+<span class="hl ppc">#include &lt;Common/iLogger&gt;</span>
+<span class="hl ppc">#include &lt;Common/iRegistry&gt;</span>
+<span class="hl ppc">#include &lt;Common/iApp&gt;</span>
+
+<span class="hl ppc">#include &lt;QtCore&gt;</span>
+<span class="hl ppc">#include &lt;QtSql/QtSql&gt;</span>
+
+<span class="hl kwd">VER_EXPORT_VERSION_INFO</span><span class="hl opt">()</span>
+<span class="hl kwd">Q_EXPORT_PLUGIN2</span><span class="hl opt">(</span>VER_MODULE_NAME_STR<span class="hl opt">,</span> eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>Storage<span class="hl opt">::</span>Module<span class="hl opt">)</span>
+
+<span class="hl kwa">using namespace</span> eVaf<span class="hl opt">;</span>
+<span class="hl kwa">using namespace</span> eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">;</span>
+<span class="hl kwa">using namespace</span> eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>Storage<span class="hl opt">;</span>
+
+Module<span class="hl opt">::</span><span class="hl kwd">Module</span><span class="hl opt">()</span>
+    <span class="hl opt">:</span> Plugins<span class="hl opt">::</span><span class="hl kwd">iPlugin</span><span class="hl opt">()</span>
+    <span class="hl opt">,</span> <span class="hl kwd">mReady</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">setObjectName</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;%1.%2&quot;</span><span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>VER_MODULE_NAME_STR<span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>__FUNCTION__<span class="hl opt">));</span>
+
+    mStorage <span class="hl opt">=</span> <span class="hl kwa">new</span> Internal<span class="hl opt">::</span>StorageImpl<span class="hl opt">;</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s created&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+Module<span class="hl opt">::~</span><span class="hl kwd">Module</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl kwa">delete</span> mStorage<span class="hl opt">;</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s destroyed&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">bool</span> Module<span class="hl opt">::</span><span class="hl kwd">init</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> args<span class="hl opt">)</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">Q_UNUSED</span><span class="hl opt">(</span>args<span class="hl opt">);</span>
+
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>mStorage<span class="hl opt">-&gt;</span><span class="hl kwd">init</span><span class="hl opt">())</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+
+    mReady <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s initialized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">void</span> Module<span class="hl opt">::</span><span class="hl kwd">done</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    mReady <span class="hl opt">=</span> <span class="hl kwa">false</span><span class="hl opt">;</span>
+
+    mStorage<span class="hl opt">-&gt;</span><span class="hl kwd">done</span><span class="hl opt">();</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s finalized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwa">using namespace</span> eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>Storage<span class="hl opt">::</span>Internal<span class="hl opt">;</span>
+
+<span class="hl kwb">char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> StorageImpl<span class="hl opt">::</span>DbConnectionName <span class="hl opt">=</span> <span class="hl str">&quot;PswGenDB&quot;</span><span class="hl opt">;</span>
+
+<span class="hl kwb">char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> StorageImpl<span class="hl opt">::</span>DbName <span class="hl opt">=</span> <span class="hl str">&quot;PswGen.sqlite&quot;</span><span class="hl opt">;</span>
+
+StorageImpl<span class="hl opt">::</span><span class="hl kwd">StorageImpl</span><span class="hl opt">()</span>
+    <span class="hl opt">:</span> <span class="hl kwd">QAbstractListModel</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">setObjectName</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;%1.iGenerator&quot;</span><span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>VER_MODULE_NAME_STR<span class="hl opt">));</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s created&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+StorageImpl<span class="hl opt">::~</span><span class="hl kwd">StorageImpl</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s destroyed&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">init</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    <span class="hl slc">// Open the database</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>QSqlDatabase<span class="hl opt">::</span><span class="hl kwd">contains</span><span class="hl opt">(</span>DbConnectionName<span class="hl opt">)) {</span>
+        <span class="hl slc">// No database connection yet</span>
+        mDb <span class="hl opt">=</span> QSqlDatabase<span class="hl opt">::</span><span class="hl kwd">addDatabase</span><span class="hl opt">(</span><span class="hl str">&quot;QSQLITE&quot;</span><span class="hl opt">,</span> DbConnectionName<span class="hl opt">);</span>
+        mDb<span class="hl opt">.</span><span class="hl kwd">setDatabaseName</span><span class="hl opt">(</span>Common<span class="hl opt">::</span>iApp<span class="hl opt">::</span><span class="hl kwd">instance</span><span class="hl opt">()-&gt;</span><span class="hl kwd">dataRootDir</span><span class="hl opt">() +</span> DbName<span class="hl opt">);</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(!</span>mDb<span class="hl opt">.</span><span class="hl kwd">open</span><span class="hl opt">()) {</span>
+            QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+            <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to open database : %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+            <span class="hl kwa">return false</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+    <span class="hl kwa">else</span> <span class="hl opt">{</span>
+        <span class="hl slc">// Database connection already exists</span>
+        mDb <span class="hl opt">=</span> QSqlDatabase<span class="hl opt">::</span><span class="hl kwd">database</span><span class="hl opt">(</span>DbConnectionName<span class="hl opt">);</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl slc">// Create tables if necessary</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span><span class="hl kwd">createTables</span><span class="hl opt">())</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+
+    <span class="hl slc">// Load data</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span><span class="hl kwd">loadData</span><span class="hl opt">())</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+
+    <span class="hl slc">/// Register our interface</span>
+    Common<span class="hl opt">::</span>iRegistry<span class="hl opt">::</span><span class="hl kwd">instance</span><span class="hl opt">()-&gt;</span><span class="hl kwd">registerInterface</span><span class="hl opt">(</span><span class="hl str">&quot;iStorage&quot;</span><span class="hl opt">,</span> <span class="hl kwa">this</span><span class="hl opt">);</span>
+
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s initialized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">void</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">done</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    mData<span class="hl opt">.</span><span class="hl kwd">clear</span><span class="hl opt">();</span>
+    <span class="hl kwd">EVAF_INFO</span><span class="hl opt">(</span><span class="hl str">&quot;%s finalized&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span><span class="hl kwd">objectName</span><span class="hl opt">()));</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">)</span>
+<span class="hl opt">{</span>
+    <span class="hl kwd">EVAF_TEST_X</span><span class="hl opt">(</span>data<span class="hl opt">,</span> <span class="hl str">&quot;Data cannot be null&quot;</span><span class="hl opt">);</span>
+    <span class="hl kwd">EVAF_TEST_X</span><span class="hl opt">(!</span>name<span class="hl opt">.</span><span class="hl kwd">isEmpty</span><span class="hl opt">(),</span> <span class="hl str">&quot;Name cannot be empty&quot;</span><span class="hl opt">);</span>
+
+    <span class="hl slc">// Is it an update or a new data record?</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>mData<span class="hl opt">.</span><span class="hl kwd">constFind</span><span class="hl opt">(</span>name<span class="hl opt">) !=</span> mData<span class="hl opt">.</span><span class="hl kwd">constEnd</span><span class="hl opt">()) {</span>
+        <span class="hl slc">// This is an update</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">modified</span><span class="hl opt">()) {</span>
+            QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+            <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;UPDATE data SET length =</span> <span class="hl esc">\'</span><span class="hl str">%1</span><span class="hl esc">\'</span><span class="hl str">, flags =</span> <span class="hl esc">\'</span><span class="hl str">%2</span><span class="hl esc">\'</span> <span class="hl str">WHERE name =</span> <span class="hl esc">\'</span><span class="hl str">%3</span><span class="hl esc">\'</span><span class="hl str">;&quot;</span><span class="hl opt">)</span>
+                            <span class="hl opt">.</span><span class="hl kwd">arg</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">length</span><span class="hl opt">()).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">flags</span><span class="hl opt">()).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>name<span class="hl opt">))) {</span>
+                QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+                <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to update</span> <span class="hl esc">\'</span><span class="hl str">%s</span><span class="hl esc">\'</span> <span class="hl str">: %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>name<span class="hl opt">),</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+                <span class="hl kwa">return false</span><span class="hl opt">;</span>
+            <span class="hl opt">}</span>
+        <span class="hl opt">}</span>
+    <span class="hl opt">}</span>
+    <span class="hl kwa">else</span> <span class="hl opt">{</span>
+        <span class="hl slc">// Store to the database</span>
+        QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+        <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl kwd">QString</span><span class="hl opt">(</span><span class="hl str">&quot;INSERT INTO data (name, length, flags) VALUES (</span><span class="hl esc">\'</span><span class="hl str">%1</span><span class="hl esc">\'</span><span class="hl str">, %2, %3);&quot;</span><span class="hl opt">)</span>
+                            <span class="hl opt">.</span><span class="hl kwd">arg</span><span class="hl opt">(</span>name<span class="hl opt">).</span><span class="hl kwd">arg</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">length</span><span class="hl opt">())</span>
+                            <span class="hl opt">.</span><span class="hl kwd">arg</span><span class="hl opt">(</span><span class="hl kwb">int</span><span class="hl opt">(</span>data<span class="hl opt">-&gt;</span><span class="hl kwd">flags</span><span class="hl opt">())))) {</span>
+            QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+            <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to insert</span> <span class="hl esc">\'</span><span class="hl str">%s</span><span class="hl esc">\'</span> <span class="hl str">: %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>name<span class="hl opt">),</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+            <span class="hl kwa">return false</span><span class="hl opt">;</span>
+        <span class="hl opt">}</span>
+
+        <span class="hl slc">// Store also into the local hash</span>
+        mData<span class="hl opt">.</span><span class="hl kwd">insert</span><span class="hl opt">(</span>name<span class="hl opt">,</span> data<span class="hl opt">);</span>
+
+        <span class="hl slc">// Reset the model</span>
+        <span class="hl kwd">reset</span><span class="hl opt">();</span>
+    <span class="hl opt">}</span>
+
+    data<span class="hl opt">-&gt;</span><span class="hl kwd">reset</span><span class="hl opt">();</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span>
+
+QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span>
+<span class="hl opt">{</span>
+    QMap<span class="hl opt">&lt;</span>QString<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt; &gt;::</span>const_iterator it <span class="hl opt">=</span> mData<span class="hl opt">.</span><span class="hl kwd">constFind</span><span class="hl opt">(</span>name<span class="hl opt">);</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>it <span class="hl opt">!=</span> mData<span class="hl opt">.</span><span class="hl kwd">constEnd</span><span class="hl opt">())</span>
+        <span class="hl kwa">return</span> it<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">();</span>
+    <span class="hl kwa">else</span>
+        <span class="hl kwa">return</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;();</span>
+<span class="hl opt">}</span>
+
+QVariant StorageImpl<span class="hl opt">::</span><span class="hl kwd">data</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> index<span class="hl opt">,</span> <span class="hl kwb">int</span> role<span class="hl opt">)</span> <span class="hl kwb">const</span>
+<span class="hl opt">{</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>index<span class="hl opt">.</span><span class="hl kwd">isValid</span><span class="hl opt">() ||</span> index<span class="hl opt">.</span><span class="hl kwd">row</span><span class="hl opt">() &lt;</span> <span class="hl num">0</span> <span class="hl opt">||</span> index<span class="hl opt">.</span><span class="hl kwd">row</span><span class="hl opt">() &gt;=</span> mData<span class="hl opt">.</span><span class="hl kwd">size</span><span class="hl opt">() ||</span> index<span class="hl opt">.</span><span class="hl kwd">column</span><span class="hl opt">() !=</span> <span class="hl num">0</span><span class="hl opt">)</span>
+        <span class="hl kwa">return</span> <span class="hl kwd">QVariant</span><span class="hl opt">();</span>
+
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>role <span class="hl opt">==</span> Qt<span class="hl opt">::</span>EditRole <span class="hl opt">||</span> role <span class="hl opt">==</span> Qt<span class="hl opt">::</span>DisplayRole<span class="hl opt">)</span>
+        <span class="hl kwa">return</span> mData<span class="hl opt">.</span><span class="hl kwd">keys</span><span class="hl opt">().</span><span class="hl kwd">at</span><span class="hl opt">(</span>index<span class="hl opt">.</span><span class="hl kwd">row</span><span class="hl opt">());</span>
+
+    <span class="hl kwa">return</span> <span class="hl kwd">QVariant</span><span class="hl opt">();</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">createTables</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl str">&quot;SELECT name FROM sqlite_master WHERE type=</span><span class="hl esc">\'</span><span class="hl str">table</span><span class="hl esc">\'</span> <span class="hl str">AND name=</span><span class="hl esc">\'</span><span class="hl str">data</span><span class="hl esc">\'</span><span class="hl str">;&quot;</span><span class="hl opt">)) {</span>
+        QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+        <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to query database : %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwa">if</span> <span class="hl opt">(</span>q<span class="hl opt">.</span><span class="hl kwd">isActive</span><span class="hl opt">() &amp;&amp;</span> q<span class="hl opt">.</span><span class="hl kwd">isSelect</span><span class="hl opt">() &amp;&amp;</span> q<span class="hl opt">.</span><span class="hl kwd">first</span><span class="hl opt">())</span>
+        <span class="hl kwa">return true</span><span class="hl opt">;</span> <span class="hl slc">// We already have a table called 'data'</span>
+
+    <span class="hl slc">// Create the 'data' table</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl str">&quot;CREATE TABLE data (name text primary key not null, length integer, flags integer);&quot;</span><span class="hl opt">)) {</span>
+        QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+        <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to create table</span> <span class="hl esc">\'</span><span class="hl str">data</span><span class="hl esc">\'</span> <span class="hl str">: %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span>
+
+<span class="hl kwb">bool</span> StorageImpl<span class="hl opt">::</span><span class="hl kwd">loadData</span><span class="hl opt">()</span>
+<span class="hl opt">{</span>
+    QSqlQuery <span class="hl kwd">q</span><span class="hl opt">(</span>mDb<span class="hl opt">);</span>
+    <span class="hl kwa">if</span> <span class="hl opt">(!</span>q<span class="hl opt">.</span><span class="hl kwd">exec</span><span class="hl opt">(</span><span class="hl str">&quot;SELECT name, length, flags FROM data;&quot;</span><span class="hl opt">)) {</span>
+        QSqlError err <span class="hl opt">=</span> mDb<span class="hl opt">.</span><span class="hl kwd">lastError</span><span class="hl opt">();</span>
+        <span class="hl kwd">EVAF_ERROR</span><span class="hl opt">(</span><span class="hl str">&quot;Failed to query database : %s&quot;</span><span class="hl opt">,</span> <span class="hl kwd">qPrintable</span><span class="hl opt">(</span>err<span class="hl opt">.</span><span class="hl kwd">text</span><span class="hl opt">()));</span>
+        <span class="hl kwa">return false</span><span class="hl opt">;</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwa">while</span> <span class="hl opt">(</span>q<span class="hl opt">.</span><span class="hl kwd">next</span><span class="hl opt">()) {</span>
+        QString name <span class="hl opt">=</span> q<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">).</span><span class="hl kwd">toString</span><span class="hl opt">();</span>
+        QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">data</span><span class="hl opt">(</span><span class="hl kwa">new</span> Storage<span class="hl opt">::</span><span class="hl kwd">Data</span><span class="hl opt">(</span>name<span class="hl opt">,</span> q<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">(</span><span class="hl num">1</span><span class="hl opt">).</span><span class="hl kwd">toInt</span><span class="hl opt">(),</span> <span class="hl kwd">uint</span><span class="hl opt">(</span>q<span class="hl opt">.</span><span class="hl kwd">value</span><span class="hl opt">(</span><span class="hl num">2</span><span class="hl opt">).</span><span class="hl kwd">toInt</span><span class="hl opt">())));</span>
+        mData<span class="hl opt">.</span><span class="hl kwd">insert</span><span class="hl opt">(</span>name<span class="hl opt">,</span> data<span class="hl opt">);</span>
+    <span class="hl opt">}</span>
+
+    <span class="hl kwd">reset</span><span class="hl opt">();</span>
+
+    <span class="hl kwa">return true</span><span class="hl opt">;</span>
+<span class="hl opt">}</span></pre>
+
+        <p>Next -- <a href="pswgen08.html">Building Storage Module</a>.</p>
+
+    </body>
+</html>
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+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html lang="et" xmlns="http://www.w3.org/1999/xhtml" xml:lang="et">
+
+    <head>
+        <meta http-equiv="CONTENT-TYPE" content="text/html; charset=utf-8" />
+        <title>eVaf Tutorial - 08 - Building Storage Module</title>
+        <meta name="Author" content="Enar Väikene" />
+        <meta name="description" content="eVaf Tutorial" />
+        <meta name="keywords" content="evaf c++ application development framework tutorial password generator" />
+        <link rel="StyleSheet" href="evaf.css" type="text/css" media="all" />
+        <link rel="StyleSheet" href="highlight.css" type="text/css" media="all" />
+    </head>
+
+    <body>
+
+        <h1>eVaf Tutorial</h1>
+
+        <h2>08 - Buiding Storage Module</h2>
+
+        <h3>CMakeLists.txt</h3>
+
+        <p>Copy an existing <tt>CMakeLists.txt</tt> file from the <tt>Generator</tt> module:</p>
+
+        <pre>evaf/src/apps/PswGen/Storage $ <code>cp ../CMakeLists.txt .</code></pre>
+
+        <p>We only need to modify the <tt>TARGET</tt> variable and set <tt>QT_USE_QTSQL</tt> to <tt>TRUE</tt>:</p>
+
+        <pre class="hl"><span class="hl com"># Name of the target</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>TARGET PswStorage<span class="hl opt">)</span>
+
+<span class="hl com"># Qt modules</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>QT_USE_QTSQL TRUE<span class="hl opt">)</span></pre>
+
+        <p>Here is the final <tt>CMakeLists.txt</tt> file:</p>
+
+<pre class="hl"><span class="hl com"># src/apps/PswGen/Storage/CMakeLists.txt</span>
+
+<span class="hl com"># Name of the target</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>TARGET PswStorage<span class="hl opt">)</span>
+
+<span class="hl com"># Qt modules</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>QT_USE_QTSQL TRUE<span class="hl opt">)</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>QT_DONT_USE_QTGUI TRUE<span class="hl opt">)</span>
+<span class="hl kwa">include</span><span class="hl opt">(</span><span class="hl kwd">${QT_USE_FILE}</span><span class="hl opt">)</span>
+
+<span class="hl com"># Include directories</span>
+<span class="hl kwa">include_directories</span><span class="hl opt">(</span><span class="hl kwd">${eVaf_INCLUDE}<span class="hl opt">)</span>
+
+<span class="hl com"># Required eVaf libraries</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>eVaf_LIBRARIES CommonLib PluginsLib<span class="hl opt">)</span>
+
+<span class="hl com"># Source files</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>SRCS
+    module.cpp
+<span class="hl opt">)</span>
+
+<span class="hl com"># Header files for the Qt meta-object compiler</span>
+<span class="hl kwa">set</span><span class="hl opt">(</span>MOC_HDRS
+    module.h
+<span class="hl opt">)</span>
+
+<span class="hl com"># Version info resource file for Windows builds</span>
+<span class="hl kwa">if</span><span class="hl opt">(</span><span class="hl kwb">WIN32</span><span class="hl opt">)</span>
+    <span class="hl kwa">set</span><span class="hl opt">(</span>SRCS <span class="hl kwd">${SRCS}</span> version.rc<span class="hl opt">)</span>
+<span class="hl kwa">endif</span><span class="hl opt">(</span><span class="hl kwb">WIN32</span><span class="hl opt">)</span>
+
+<span class="hl com"># Run the Qt meta-object compiler</span>
+<span class="hl kwd">qt4_wrap_cpp</span><span class="hl opt">(</span>MOC_SRCS <span class="hl kwd">${MOC_HDRS}</span><span class="hl opt">)</span>
+
+<span class="hl com"># Compile the module</span>
+<span class="hl kwa">add_library</span><span class="hl opt">(</span><span class="hl kwd">${TARGET}</span> <span class="hl kwb">SHARED</span> <span class="hl kwd">${SRCS} ${MOC_SRCS}</span><span class="hl opt">)</span>
+
+<span class="hl com"># Link the module</span>
+<span class="hl kwa">target_link_libraries</span><span class="hl opt">(</span><span class="hl kwd">${TARGET} ${QT_LIBRARIES} ${eVaf_LIBRARIES}</span><span class="hl opt">)</span></pre>
+
+        <p>Open the <tt>CMakeLists.txt</tt> file in the parent directory and add the command to include the <tt>Storage</tt>
+        sub-directory:</p>
+
+        <pre class="hl"><span class="hl com"># src/apps/PswGen/CMakeLists.txt</span>
+<span class="hl com"># ...</span>
+<span class="hl kwa">add_subdirectory</span><span class="hl opt">(</span>Storage<span class="hl opt">)</span></pre>
+
+        <h3>Building the module</h3>
+
+        <p>Go to the previously made <tt>build</tt> directory and build the module:</p>
+
+        <pre>evaf $ <code>cd build</code>
+evaf/build $ <code>make PswStorage</code></pre>
+
+        <p>Check the <tt>bin</tt> directory, which should now contain a new library:</p>
+
+        <pre>evaf/build $ <code>ls bin</code>
+libCommonLib.so*  libPluginsLib.so*  libPswGen.so*  <b>libPswStorage.so*</b>
+evaf/build $</pre>
+
+        <p>In the next section <a href="pswgen09.html">09 - GUI Module</a> we write the Graphical User Interface Module.</p>
+
+    </body>
+</html>