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  1. #1

    Model/view, apply a filter on model


    I am subclassing QSqlTableModel for a model used by a QListView.
    This model represents data stored in a SQLite database.
    In this database I have a flag field (let say an int field at column 0).
    I want my model to present data depending on the flag value, in other word I want to apply a filter on my model.
    So I have a public method setFilter(int flag) to set the current filter on flag value, and I want my model to present only the data (rows) that match this value.

    Let say my db is like:
    flag | value
    0 | foo
    1 | bar
    After setFilter(0) I want my model to present only:
    flag | value
    0 | foo
    The code :
    MyModel::MyModel(QObject *parent) :
    MyModel::setFilter(int flag) 
    currentFlag = flag; // currentFlag is MyModel class member
    MyModel::data(const QModelIndex & index, int role ) const
        if( index.model()->data(index.sibling(index.row(),0)) == currentFlag) // if the current index points to a row with flag column equals to the current filter, return the value, but this leads to infinite recursive call 
            return QSqlTableModel::data(index, role);
        else return QVariant(); // else return an invalid data
    Problem is, to check the flag value I have to call data() inside the data() method, which leads to infinite recursive call.
    How can I solve this ? How can I check value of another ModelIndex in the QAbstractItemModel::data() method ? Is it possible or am I using Model/view classes the wrong way ?

    Hope everything is clear.

  2. #2
    Super Contributor
    Join Date
    Oct 2009

    Re: Model/view, apply a filter on model

    I believe it's probably easier to use setFilter( const QString & filter )

  3. #3

    Re: Model/view, apply a filter on model

    Thanks, that's what I was looking for, missed it from the doc.
    Another solution I found is to subclass QSortFilterProxyModel.

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