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Correct usage of QAbstractItemModel with a recursive data structure



  • I have an recursive data structure, to hold configuration data for a sound synthesiser. I already have a means to serialise this. Now I wish to provide a viewing/editing interface using the Qt model/view framework. The data structure may be thought of as an archive, i.e. it is structured rather like a filesystem. There are data items held in sections, and sections may contain subsections, like this:

    @
    instruments/
    Violin/
    config
    builder
    Viola/
    config
    builder
    Cello/
    config
    builder
    @

    The data structure is currently implemented using std::map, but I could use QMap. Items are looked up by name. Data items are Lua code stored in std::strings, but I think QByteArray would be better, as it can do compression and more.

    An obvious way to present this data is with a QTreeView, and a subclass of QStandardItemModel could be used as the interface between the view and the data. But how do I access my data items via the model? Should each QStandardItem hold a pointer to a data or section item? Or should I keep a copy of an item's name in its corresponding QStandardItem, so I can look up items in maps on demand?



  • I'd advise againt using QStandardItemModel for this. You'll end up duplicating your data structure.

    Instead, think of your model as an adaptor between your existing data store, and the Qt model/view API. So, have your model use your existing, underlying data model instead of re-doing the work. That directly answers your question: there is no data in your model, so also no need to keep copies.


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