QComboBox not calling Delegate methods

Question

I want to customize a `QComboBox` by inserting `QWidgets` (instead of strings) through a model and a delegate: ``` QComboBox *cb = new QComboBox(this); FeatureModel *featureModel = new FeatureModel(cb); cb->setModel(featureModel); ComboBoxItemDelegate *comboBoxItemDelegate = new ComboBoxItemDelegate(cb); cb->setItemDelegate(comboBoxItemDelegate); ``` FeatureModel inherits from QAbstractListModel and ComboBoxItemDelegate inherits from QStyledItemDelegate. The problem is that the delegates methods are never called and therefore my custom widget is not inserted (I only see the strings of the `FeatureModel`). However, if I use a `QTableView` instead of a `QComboBox`, it works as it should. Does someone know where the error lies? Am I missing some important aspect of the QT Model/View concept? EDIT: Here is my Delegate. Except of the constructor (of course), none of the following methods are called (no ouput on the console). ``` ComboBoxItemDelegate::ComboBoxItemDelegate(QObject *parent) :…

Accepted Answer

I think I found the problem.

First, make sure the view in the `QComboBox` allows editing:

```
cb->view()->setEditTriggers(QAbstractItemView::AllEditTriggers);
```

I'm not sure if that's a good practice, but that was the only way I could make it work. The default value for `editTriggers` is `QAbstractItemView::NoEditTriggers`

Second, make sure your model allows editing:

```
Qt::ItemFlags MyModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return Qt::ItemIsEnabled;

return QAbstractItemModel::flags(index) | Qt::ItemIsEditable;
}

bool MyModel::setData(const QModelIndex &index,
                           const QVariant &value, int role)
{
    if (index.isValid() && role == Qt::EditRole) {
        // Modify data..

emit dataChanged(index, index);
        return true;
    }
    return false;
}
```

It has a problem, though. The first time you see the `ComboBox`, you can change the current item text, and it won't call the delegate methods for editing. You have to select one item and then you'll be able to edit it.

Anyway, I find that using a `QComboBox` for editable items is counter-intuitive. Are you sure that you need a `QComboBox` for this task?

Hope it helps

QComboBox not calling Delegate methods

Solution

Problem