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  1. Qt
  2. QTBUG-81076

MapItemView crashes the application after beginMoveRows/endMoveRows in underlying model

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    • Platform/s:
      All

      Description

      Implemented QML Dynamic View Ordering by Dragging View Items using this Qt tutorial: QML Dynamic View Ordering Tutorial. Only changed original underlying model which is QAbstractListModel descendant in our case. Model stores data in a QList<QObject*> objectList; field type.

      Was necessary to change items order automatically in original underlying model as well (not only in DelegateModel) for other C++ and QML consumers where this order matters. Implemented this by adding void ObjectListModel::move(int from, int to) to the ObjectListModel implementation like I've mentioned here on Stackoverflow:

      void ObjectListModel::move(int from, int to)
      {
          if(0 <= from && from < count() && 0 <= to && to < count() && from != to) {
              if(from == to - 1) // Allow item moving to the bottom
                  to = from++;
      
              beginMoveRows(QModelIndex(), from, from, QModelIndex(), to);
              objectList.move(from, to);
              endMoveRows();
          }
      }
      

      However another model consumer like MapItemView fails to use the model after beginMoveRows/endMoveRows calls: moved indicator item disappeared on the map (not destroyed or visibility changed) and other manipulations with the item crashes the app.

       Map {
           ...
           MapItemView {
               model: objectListModel
      
               delegate: SomeItemIndicator {
               }
           }
       }
      

      Think Qt bug. Some other hacks like emitting dataChanged() signal, etc do not help as well.

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              Assignee:
              paangele Paolo Angelelli
              Reporter:
              jirauser39314 user-45b5b (Inactive)
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                Created:
                Updated:

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