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POHow to create artificial nodes in QAbstractItemModel for QTreeView
 

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    <p>my question is about Qt and its <a href="http://qt.nokia.com/doc/4.6/qabstractitemmodel.html" rel="nofollow noreferrer">QAbstractItemModel</a>.</p> <p>I have a map of strings and doubles (<code>std::map&lt;stringclass, double&gt;</code>) which I would like to present in a Qt widget. While I could use <a href="http://qt.nokia.com/doc/4.6/qtableview.html" rel="nofollow noreferrer">QTableView</a> for that, I would like to exploit the fact that the keys of the map are of form "<code>abc.def.ghi</code>" where there can be multiple strings that can start with "<code>abc.def</code>" and even more that start with "<code>abc</code>".</p> <p>So I would like to setup a tree data model to present the items in a <a href="http://qt.nokia.com/doc/4.6/qtreeview.html" rel="nofollow noreferrer">QTreeView</a> like</p> <pre><code>(-) abc |--(-)def |--ghi 3.1415 |--jkl 42.0815 |--(+)pqr |--(+)xyz </code></pre> <p>The keys of my <code>std::map</code> are the leaves of the tree, where all other nodes would be temporary and auxillary constructs to support the folding for user convenience. </p> <p>Unfortunately, the methods <code>rowCount</code>, <code>index</code>, <code>columnCount</code>, and <code>data</code> have const-modifiers, so I cannot simply setup a auxillary data structure for the headers inside my <a href="http://qt.nokia.com/doc/4.6/qabstractitemmodel.html" rel="nofollow noreferrer">QAbstractItemModel</a> derivate and change that data structure in there.</p> <p>What would be the best practice for that? Should I setup another class layer between my <code>std::map</code> and the <a href="http://qt.nokia.com/doc/4.6/qabstractitemmodel.html" rel="nofollow noreferrer">QAbstractItemModel</a> or is there a smarter way to do this?</p> <hr> <p>Edit 1: The <code>std::map</code> can change while the <a href="http://qt.nokia.com/doc/4.6/qtreeview.html" rel="nofollow noreferrer">QTreeView</a> is shown and used, so the auxillary nodes might be thrown away and reconstructed. My assumption is that the best way to handle this is to restructure the <a href="http://qt.nokia.com/doc/4.6/qabstractitemmodel.html" rel="nofollow noreferrer">QAbstractItemModel</a> - or should I simply throw that model away and assign a newly constructred one to the <a href="http://qt.nokia.com/doc/4.6/qtreeview.html" rel="nofollow noreferrer">QTreeView</a>? In that case I could set-up all nodes within the constructor without being bothered by the const-ness of the methods, I guess.</p>
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