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<title>XmlRole QML Type | Qt XML Patterns 5.12.6</title>
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<td >Qt 5.12</td><td ><a href="qtxmlpatterns-index.html">Qt XML Patterns</a></td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtxmlpatterns-index.html">Qt 5.12.6 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#properties">Properties</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">XmlRole QML Type</h1>
<span class="subtitle"></span>
<!-- $$$XmlRole-brief -->
<p>For specifying a role to an <a href="qml-qtquick-xmllistmodel-xmllistmodel.html">XmlListModel</a>. <a href="#details">More...</a></p>
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<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> Import Statement:</td><td class="memItemRight bottomAlign"> import QtQuick.XmlListModel 2.12</td></tr></table></div><ul>
<li><a href="qml-qtquick-xmllistmodel-xmlrole-members.html">List of all members, including inherited members</a></li>
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<a name="properties"></a>
<h2 id="properties">Properties</h2>
<ul>
<li class="fn"><b><b><a href="qml-qtquick-xmllistmodel-xmlrole.html#isKey-prop">isKey</a></b></b> : bool</li>
<li class="fn"><b><b><a href="qml-qtquick-xmllistmodel-xmlrole.html#name-prop">name</a></b></b> : string</li>
<li class="fn"><b><b><a href="qml-qtquick-xmllistmodel-xmlrole.html#query-prop">query</a></b></b> : string</li>
</ul>
<!-- $$$XmlRole-description -->
<a name="details"></a>
<h2 id="details">Detailed Description</h2>
<p><b>See also </b>Qt QML.</p>
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<h2>Property Documentation</h2>
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<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>
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<div class="qmlitem"><div class="qmlproto">
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<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>
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</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>
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</pre>
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<br/>
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<div class="qmlitem"><div class="qmlproto">
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<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>
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</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">
</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">
XmlListModel {
id: model
...
// XmlRole queries will be made on <book> elements
query: "/catalog/book"
// query the book title
XmlRole { name: "title"; query: "title/string()" }
// query the book's year
XmlRole { name: "year"; query: "year/number()" }
// query the book's type (the '@' indicates 'type' is an attribute, not an element)
XmlRole { name: "type"; query: "@type/string()" }
// query the book's first listed author (note in XPath the first index is 1, not 0)
XmlRole { name: "first_author"; query: "author[1]/string()" }
// query the wanted attribute as a boolean
XmlRole { name: "wanted"; query: "boolean(@wanted)" }
}
</pre>
<p>Accessing the model data for the above roles from a delegate:</p>
<pre class="qml">
ListView {
width: 300; height: 200
model: model
delegate: Column {
Text { text: title + " (" + type + ")"; font.bold: wanted }
Text { text: first_author }
Text { text: year }
}
</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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