Delegates and relational table views

i92guboj

Hi :)

I am using QSqlRelationalDelegate into a QSqlRelationalTableView, which works fine.

However I'd like the combo box to be able to filter as I type, because it holds several thousands of items. I'd like to know if this can be implemented with this kind of delegate or if I should be looking at QStyledDelegate or something else instead.

Having filter capabilities in the delegate would also be nice, though I think I can solve that in some other way.

I have read the documentation, but the QSqlRelationalDelegate page is so so simple that I am really wondering if that's really all that there's to it. Still learning as I go :)

Thanks everyone.

raven-worx

so you have an editable comobox as an editor?
If so you can use QComboBox::setCompleter() on the editor widget (combobox)

i92guboj

[quote author="raven-worx" date="1376469355"]so you have an editable comobox as an editor?
If so you can use QComboBox::setCompleter() on the editor widget (combobox)[/quote]

I don't really know. It's a combo box, but I have no idea how qt handles this internally. I am using QSqlRelationalDelegate, this way:

[code]
ui->tableView_cascosYAccesorios->setItemDelegate(new QSqlRelationalDelegate(ui->tableView_cascosYAccesorios));
[/code]

With whatever "editor" it uses by default. I have also tried to declare the delegate separately, but I have no idea how to access its editor, if that's even possible.

That's why I am wondering if I should use another kind of delegate which is more flexible...

Thanks for your help :)

i92guboj

Right now, I have this:

[code]
class MySqlDelegate : public QSqlRelationalDelegate
{
Q_OBJECT
public:
explicit MySqlDelegate(QObject *parent = 0);

signals:

public slots:
void setEditorData ( QWidget * editor, const QModelIndex & index ) const
{
QSqlRelationalDelegate::setEditorData(editor, index);

    QComboBox* comboBox = qobject_cast<QComboBox*>(editor);
    comboBox->setEditable(true);
    if( comboBox )
    {
        QCompleter* completer = new QCompleter(comboBox);
        completer->setCompletionColumn(index.column());
        completer->setCompletionMode(QCompleter::PopupCompletion);
        completer->setWrapAround(true);
        completer->setMaxVisibleItems(10);
        completer->setCaseSensitivity(Qt::CaseInsensitive);
        comboBox->setCompleter(completer);
        connect(comboBox, SIGNAL(editTextChanged(QString)),
                completer, SLOT(setCompletionPrefix(QString)));
    }
}

};
[/code]

It seems the setEditable(true) bit got me as far as to being able to actually edit the combobox, however the filtering doesn't seem to work and I get no popup.

The popup works ok and shows all the elements if I click the down arrow icon, of course. Which is why I know that the combobox has been populated as it should.

I also tried connecting the things in some manner, but it didn't make a difference. Please, don't lauch at me :)

It's my first time with delegates, so, you know... :P

Thank you everyone.

raven-worx

so did it solve your problem or do you still have an issue?

i92guboj

Nope, sorry for not being so clear.

It doesn't seem to actually filter anything, and the popup doesn't appear as I write.

I'd also like the QComboBox field empty on the first keypress, but that's the not my bigest problem right now, and I should be able to figure that out eventually (or so I hope).

I am having some trouble to find QCompleter/QComboBox examples in the net, plus I don't really know what QSqlRelationalDelegate does under the hood.

I think I need some coffee, then I'll get back to this ;)

raven-worx

just some additions to your code:
put the "comboBox->setEditable(true)" inside the if statement to avoid possible crashes.

I don't think that you need to connect the completer explicitly. It should be enough to just set it on the combobox.

i92guboj

[quote author="raven-worx" date="1376490168"]just some additions to your code:
put the "comboBox->setEditable(true)" inside the if statement to avoid possible crashes.[/quote]

Thanks, that makes sense.

[quote]
I don't think that you need to connect the completer explicitly. It should be enough to just set it on the combobox.[/quote]

That's what I thought. After all, I am subclassing a completelly functional critter, but it doesn't seem to do a thing (it doesn't do a thing after the explicit connection either, so...).

The items are there, in the popup and I can select them with the mouse. But they are not affected by any kind of filtering, it doesn't matter what I write in the box.

raven-worx

ok i think the QCompleter is missing it's values ;)

Try this:
@
class MySqlDelegate : public QSqlRelationalDelegate
{
Q_OBJECT

public:
    explicit MySqlDelegate(QObject *parent = 0);
  
    void setEditorData ( QWidget * editor, const QModelIndex & index ) const
    {
        QSqlRelationalDelegate::setEditorData(editor, index);
 
        QComboBox* comboBox = qobject_cast<QComboBox*>(editor);
        if( comboBox )
        {
            comboBox->setEditable(true);

            QCompleter* completer = new QCompleter(index.model(), comboBox);
            completer->setCompletionColumn(index.column());
             completer->setCompletionMode(QCompleter::PopupCompletion);
            completer->setWrapAround(true);
            completer->setMaxVisibleItems(10);
            completer->setCaseSensitivity(Qt::CaseInsensitive);
            comboBox->setCompleter(completer);
        }
    }
};

@

i92guboj

I can't seem to be able to do that. I can't use setModel() either, not on a const QModelIndex& argument... I'll continue trying things, but I'd really appreciate a good book on models, indexes, records, and that stuff. Right now it's all a wonderful spaghetti to me :P

Your help is much appreciated. Thanks again.

i92guboj

It seems that we also need to reimplement the method for the model. I ended up using this:

http://qt-project.org/wiki/QSqlRelationalDelegate-subclass-for-QSqlRelationalTableModel

Which "just works" after setting the edit capabilities to true, just as before. I promise to get back to this some day, but I've lost a whole day in this and I am in a bit of a hurry now.

Thank you a ton, this has been quite illustrative, but for now it's a bit over my head. :(