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<title>XmlRole QML Type | Qt Quick 5.9</title>
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<td >Qt 5.9</td><td ><a href="qtquick-index.html">Qt Quick</a></td><td ><a href="qtquick-qmlmodule.html">QML Types</a></td><td >XmlRole QML Type</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right">Qt 5.9.4 Reference Documentation</td>
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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#properties">Properties</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
</ul>
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<h1 class="title">XmlRole QML Type</h1>
<span class="subtitle"></span>
<!-- $$$XmlRole-brief -->
<p>For specifying a role to an <a href="qml-qtquick-xmllistmodel-xmllistmodel.html">XmlListModel</a> <a href="#details">More...</a></p>
<!-- @@@XmlRole -->
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> Import Statement:</td><td class="memItemRight bottomAlign"> import QtQuick.XmlListModel 2.0</td></tr></table></div><ul>
<li><a href="qml-qtquick-xmllistmodel-xmlrole-members.html">List of all members, including inherited members</a></li>
</ul>
<a name="properties"></a>
<h2 id="properties">Properties</h2>
<ul>
<li class="fn"><b><b><a href="qml-qtquick-xmllistmodel-xmlrole.html#isKey-prop">isKey</a></b></b> : bool</li>
<li class="fn"><b><b><a href="qml-qtquick-xmllistmodel-xmlrole.html#name-prop">name</a></b></b> : string</li>
<li class="fn"><b><b><a href="qml-qtquick-xmllistmodel-xmlrole.html#query-prop">query</a></b></b> : string</li>
</ul>
<!-- $$$XmlRole-description -->
<a name="details"></a>
<h2 id="details">Detailed Description</h2>
<p><b>See also </b>Qt QML.</p>
<!-- @@@XmlRole -->
<h2>Property Documentation</h2>
<!-- $$$isKey -->
<div class="qmlitem"><div class="qmlproto">
<div class="table"><table class="qmlname">
<tr valign="top" class="odd" id="isKey-prop">
<td class="tblQmlPropNode"><p>
<a name="isKey-prop"></a><span class="name">isKey</span> : <span class="type">bool</span></p></td></tr>
</table></div>
</div><div class="qmldoc"><p>Defines whether this is a key role. Key roles are used to determine whether a set of values should be updated or added to the XML list model when <a href="qml-qtquick-xmllistmodel-xmllistmodel.html#reload-method">XmlListModel::reload()</a> is called.</p>
<p><b>See also </b><a href="qml-qtquick-xmllistmodel-xmllistmodel.html">XmlListModel</a>.</p>
</div></div><!-- @@@isKey -->
<br/>
<!-- $$$name -->
<div class="qmlitem"><div class="qmlproto">
<div class="table"><table class="qmlname">
<tr valign="top" class="odd" id="name-prop">
<td class="tblQmlPropNode"><p>
<a name="name-prop"></a><span class="name">name</span> : <span class="type">string</span></p></td></tr>
</table></div>
</div><div class="qmldoc"><p>The name for the role. This name is used to access the model data for this role.</p>
<p>For example, the following model has a role named "title", which can be accessed from the view's delegate:</p>
<pre class="qml">
<span class="type"><a href="qml-qtquick-xmllistmodel-xmllistmodel.html">XmlListModel</a></span> {
<span class="name">id</span>: <span class="name">xmlModel</span>
<span class="comment">// ...</span>
<span class="type"><a href="qml-qtquick-xmllistmodel-xmlrole.html">XmlRole</a></span> {
<span class="name">name</span>: <span class="string">"title"</span>
<span class="name">query</span>: <span class="string">"title/string()"</span>
}
}
</pre>
<pre class="qml">
<span class="type"><a href="qml-qtquick-listview.html">ListView</a></span> {
<span class="name">model</span>: <span class="name">xmlModel</span>
<span class="name">delegate</span>: <span class="name">Text</span> { <span class="name">text</span>: <span class="name">title</span> }
}
</pre>
</div></div><!-- @@@name -->
<br/>
<!-- $$$query -->
<div class="qmlitem"><div class="qmlproto">
<div class="table"><table class="qmlname">
<tr valign="top" class="odd" id="query-prop">
<td class="tblQmlPropNode"><p>
<a name="query-prop"></a><span class="name">query</span> : <span class="type">string</span></p></td></tr>
</table></div>
</div><div class="qmldoc"><p>The relative XPath expression query for this role. The query must be relative; it cannot start with a '/'.</p>
<p>For example, if there is an XML document like this:</p>
<pre class="cpp">
<?xml version="1.0" encoding="iso-8859-1" ?>
<catalog>
<book type="Online" wanted="true">
<title>Qt 5 Cadaques</title>
<year>2014</year>
<author>Juergen Bocklage-Ryannel</author>
<author>Johan Thelin</author>
</book>
<book type="Hardcover">
<title>C++ GUI Programming with Qt 4</title>
<year>2006</year>
<author>Jasmin Blanchette</author>
<author>Mark Summerfield</author>
</book>
<book type="Paperback">
<title>Programming with Qt</title>
<year>2002</year>
<author>Matthias Kalle Dalheimer</author>
</book>
</catalog>
</pre>
<p>Here are some valid XPath expressions for <a href="qml-qtquick-xmllistmodel-xmlrole.html">XmlRole</a> queries on this document:</p>
<pre class="qml">
<span class="type"><a href="qml-qtquick-xmllistmodel-xmllistmodel.html">XmlListModel</a></span> {
<span class="name">id</span>: <span class="name">model</span>
...
<span class="comment">// XmlRole queries will be made on <book> elements</span>
<span class="name">query</span>: <span class="string">"/catalog/book"</span>
<span class="comment">// query the book title</span>
<span class="type"><a href="qml-qtquick-xmllistmodel-xmlrole.html">XmlRole</a></span> { <span class="name">name</span>: <span class="string">"title"</span>; <span class="name">query</span>: <span class="string">"title/string()"</span> }
<span class="comment">// query the book's year</span>
<span class="type"><a href="qml-qtquick-xmllistmodel-xmlrole.html">XmlRole</a></span> { <span class="name">name</span>: <span class="string">"year"</span>; <span class="name">query</span>: <span class="string">"year/number()"</span> }
<span class="comment">// query the book's type (the '@' indicates 'type' is an attribute, not an element)</span>
<span class="type"><a href="qml-qtquick-xmllistmodel-xmlrole.html">XmlRole</a></span> { <span class="name">name</span>: <span class="string">"type"</span>; <span class="name">query</span>: <span class="string">"@type/string()"</span> }
<span class="comment">// query the book's first listed author (note in XPath the first index is 1, not 0)</span>
<span class="type"><a href="qml-qtquick-xmllistmodel-xmlrole.html">XmlRole</a></span> { <span class="name">name</span>: <span class="string">"first_author"</span>; <span class="name">query</span>: <span class="string">"author[1]/string()"</span> }
<span class="comment">// query the wanted attribute as a boolean</span>
<span class="type"><a href="qml-qtquick-xmllistmodel-xmlrole.html">XmlRole</a></span> { <span class="name">name</span>: <span class="string">"wanted"</span>; <span class="name">query</span>: <span class="string">"boolean(@wanted)"</span> }
}
</pre>
<p>Accessing the model data for the above roles from a delegate:</p>
<pre class="qml">
<span class="type"><a href="qml-qtquick-listview.html">ListView</a></span> {
<span class="name">width</span>: <span class="number">300</span>; <span class="name">height</span>: <span class="number">200</span>
<span class="name">model</span>: <span class="name">model</span>
<span class="name">delegate</span>: <span class="name">Column</span> {
<span class="type"><a href="qml-qtquick-text.html">Text</a></span> { <span class="name">text</span>: <span class="name">title</span> <span class="operator">+</span> <span class="string">" ("</span> <span class="operator">+</span> <span class="name">type</span> <span class="operator">+</span> <span class="string">")"</span>; <span class="name">font</span>.bold: <span class="name">wanted</span> }
<span class="type"><a href="qml-qtquick-text.html">Text</a></span> { <span class="name">text</span>: <span class="name">first_author</span> }
<span class="type"><a href="qml-qtquick-text.html">Text</a></span> { <span class="name">text</span>: <span class="name">year</span> }
}
</pre>
<p>See the <a href="http://www.w3.org/TR/xpath20/">W3C XPath 2.0 specification</a> for more information.</p>
</div></div><!-- @@@query -->
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