QCompleter in QTableView: show always, even before user input

[azrdev]

I have a QTableView showing a custom editable model. When editing strings in the view (with the default QLineEdit created by the default delegate) I want to see a suggestion of "known" predefined values for that cell. So I subclassed QStyledItemDelegate and (in createEditor()) added a QCompleter to the QLineEdit.
This works, when entering text into a cell the popup appears & I can select (with mouse or arrow keys) from the proposals. However, I'd like the popup to appear before entering anything, directly after triggering the edit.

I tried to call QCompleter::setCompletionPrefix(index.data(Qt::EditRole).toString()) and QCompleter::complete() from QStyledItemDelegate::updateEditorGeometry() and QStyledItemDelegate::setEditorData(), to no avail.

[SGaist]

Hi,

Something like completer->popup()->show(); should do what you want.

Hope it helps.

[raven-worx]

@azrdev said:

I tried to call QCompleter::setCompletionPrefix(index.data(Qt::EditRole).toString()) and QCompleter::complete()

actually this should be the correct way of showing the popup - correctly positioned and with the right completions. I guess the place where you call it is just incorrect.

Try to do it on the show event by doing the following:

QWidget* MyItemDelegate::createEditor(QWidget * parent, const QStyleOptionViewItem & option, const QModelIndex & index) const
{
        QWidget* editor = QStyledItemDelegate::createEditor(parent, option, index);
        m_Editor = editor; //member to store the current editor. Type is "QPointer<QWidget>"
        if( QLineEdit* lineEdit = qobject_cast<QLineEdit*>(editor) )
        {
             //set your completer on the lineEdit
        }
        
        return editor;
}

bool MyItemDelegate::editorEvent(QEvent * event, QAbstractItemModel * model, const QStyleOptionViewItem & option, const QModelIndex & index)
{
      if( QLineEdit* lineEdit = qobject_cast<QLineEdit*>(m_Editor) )
      {
            switch( event->type() )
            {
                 case QEvent::Show:
                 {
                         if( QCompleter* completer = lineEdit->completer() )
                         {
                                   completer->setCompletionPrefix(index.data(Qt::EditRole).toString());
                                  completer->complete();
                         }
                 }
            }
      }
      return QStyledItemDelegate::editorEvent(event, model, option, index);
}

(untested)

[azrdev]

@raven-worx said in QCompleter in QTableView: show always, even before user input:

QWidget* MyItemDelegate::createEditor(QWidget * parent, const QStyleOptionViewItem & option, const QModelIndex & index) const
...
        m_Editor = editor; //member to store the current editor. Type is "QPointer<QWidget>"
...
      if( QLineEdit* lineEdit = qobject_cast<QLineEdit*>(m_Editor) )

This does compile, because createEditor() is const, which disallows saving the editor widget in a member. Also, you assume there exists only ever one editor -- don't know if that's true/guaranteed by Qt.

[raven-worx]

@azrdev
declare the m_Editor variable as mutable.
If you do not have any special treatment with the editor in a normal view it should work.

[azrdev]

@raven-worx said in QCompleter in QTableView: show always, even before user input:

declare the m_Editor variable as mutable.

This makes it compile (even though I'm not sure about the implications), but it doesn't help me: there is no Show event handled in editorEvent ever (tested with printf-debugging - yes, before the test for QLineEdit), I'm only getting Mouse events.

---

@SGaist said in QCompleter in QTableView: show always, even before user input:

Something like completer->popup()->show(); should do what you want.

Nope, does not help.

---

I figured (using qDebug, again), the place where I should put my popup-opening call is setEditorData. In there, I receive the QLineEdit and it's QCompleter: But I cannot make it show the popup. I tried now:

completer->setCompletionPrefix(index.data(Qt::EditRole).toString());
completer->complete();
completer->popup()->show();

Note: Sometimes the popup is shown for a very short time, but immediately hides. When repeatedly entering & leaving edit mode this only works the first time.