On Sat, Apr 30, 2016 at 4:08 AM, anton <anto...@gmx.de> wrote: > Thanks Björn, > > I'll try it (actually i did the job in the rowCount() function..) > I would have preferred that the documentation be clear about this, > I mean with a detailed example :-) >
Slight aside: Since you're working with QAbstractItemModel I would highly recommend using Model Test in your debug build: https://wiki.qt.io/Model_Test I've written many QAbstractItemModel-derived classes, and I still find them hard to get right. Model Test has helped catch a lot of edge cases. > Thanks > > Anton > > Björn Schäpers wrote: > > > Am 26.04.2016 um 19:05 schrieb anton: > >> Hi, > >> > >> I have subclassed QAbstractItemModel, > >> and I want to load additionally data in the model > >> as soon as somebody clicks on the [+] > >> in the treeview to load the children of this > >> item form an external data ( web- app which gives me json data back). > >> > >> Now: > >> I reimplemented hasChildren() in the model > >> but i am not sure about the moment to load the data. > >> > >> I suppose that the rowCount() method of the model is called > >> when somebody expands an item in the view? > >> If not what is the moment when my model should ask for additional Data? > >> > >> Does there exist a small example which demonstrates how to > >> handle this in an optimal way. > >> Not sure about beginInsertRows() or layoutChanged() .. > >> I am experimenting but i get also some crashes so an > >> example project would be nice. > >> > >> Thanks > >> > >> Anton > > I think you are looking for QAbstractItemModel::canFetchMore() and > > fetchMore(). See also the last paragraph in > > http://doc.qt.io/qt-5/qabstractitemmodel.html > > > > To create models that populate incrementally, you can reimplement > > fetchMore() and canFetchMore(). If the reimplementation of fetchMore() > > adds rows to the model, beginInsertRows() and endInsertRows() must be > > called. > > > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest > --- Andy Maloney // https://asmaloney.com twitter ~ @asmaloney <https://twitter.com/asmaloney>
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