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Thread: Cannot drag children of QTreeView when first column is hidden

  1. #1
    Join Date
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    Default Cannot drag children of QTreeView when first column is hidden

    Hi,

    I've implemented a tree model on top of a QSqlTableModel via a proxy model (QSqlTableModel doesn't work well with parent/child relationships). It works great, except when I hide the first column of the view (id column). I want to hide the id column because I don't want it in the view but once I do, dragging children does not work. Any thoughts? I haven't been able to make any progress on this. code attached and below. Thanks!

    sqltreemodel.h

    Qt Code:
    1. #define TREEMODEL_H
    2.  
    3. #include <QSqlTableModel>
    4.  
    5. class sqlTreeModel : public QSqlTableModel
    6. {
    7. Q_OBJECT
    8.  
    9. public:
    10. sqlTreeModel(QObject *parent=nullptr);
    11.  
    12. virtual Qt::DropActions supportedDragActions() const { return Qt::MoveAction; }
    13. virtual Qt::DropActions supportedDropActions() const { return Qt::MoveAction; }
    14. };
    15.  
    16. #endif // TREEMODEL_H
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    mainwindow.h
    Qt Code:
    1. #ifndef MAINWINDOW_H
    2. #define MAINWINDOW_H
    3.  
    4. #include <QMainWindow>
    5. #include <QSqlError>
    6.  
    7. class QTreeView;
    8. class sqlTreeModel;
    9. class proxyTreeModel;
    10.  
    11. class MainWindow : public QMainWindow
    12. {
    13. Q_OBJECT
    14.  
    15. public:
    16. explicit MainWindow(QWidget *parent = nullptr);
    17.  
    18. private:
    19. QTreeView *treeView;
    20.  
    21. sqlTreeModel *plidModel;
    22. proxyTreeModel *proxyPlidModel;
    23. QHash<QString,QPair<int,int> > playlistVideoTracker;
    24.  
    25. QSqlError initdb();
    26. void setupModels();
    27. };
    28.  
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  2. #2
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    Default Re: Cannot drag children of QTreeView when first column is hidden

    Children in built-in Qt models are attached to the first column of the model thus when you hide it, the relationship breaks. A possible solution would be to put a proxy model on top of the sql model to reorder columns so that the id is not the first column. Or you can just remove the id column from the model using a proxy (or your existing QSqlTableModel subclass).
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

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  3. #3
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    Default Re: Cannot drag children of QTreeView when first column is hidden

    Thank you Grandmaster Wysota that did it!

    I did implement a custom model (inherited QAbstractItemModel) and create my own tree item class to manage the parent/child relationship. Is the first column therefore used by the view or delegate?

  4. #4
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    Default Re: Cannot drag children of QTreeView when first column is hidden

    I'm not sure I understand your question. If the column is visible then it is "used" by the view and the delegate. If it is hidden by the model itself, the view and the delegate know nothing about it.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


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