QComboBox Array Access

Question

I'd like to be able to access the values in my QComboBox without having to loop over the contents using itemText.

for( auto i = 0u; i < myQComboBox->count(); i++ )
{
    result[i] = myQComboBox->itemText( i );
}

Is there a way that I can get to QComboBox's underlying QList so I can just use the operator[] or even better, iterators and range based loops?

Answer 1

It appears that you're hung on the syntax: you want to replace myQComboBox->itemText(i) with myQComboBox[i]. That can be rather easily done:

// implementation
class ModelAdapter {
  QPointer<QAbstractItemModel> m_model;
public:
  explicit ModelAdapter(QComboBox & box) : m_model(box.model()) {}
  explicit ModelAdapter(QAbstractItemModel * model) : m_model(model) {}
  QVariant operator[](int i) { return m_model->index(i, 0); }
};

// point of use
ModelAdapter model(myQComboBox);
for( auto i = 0; i < myQComboBox->count(); i++ )
{
    result[i] = model[i];
}

With a good compiler, you can do the below and have it produce the same code as if you used combobox.model->index(i, 0) directly. I don't see the point of it, but hey, it's possible :)

// implementation
class Adapter {
  QAbstractItemModel* m_model;
public:
  explicit Adapter(QComboBox & box) : m_model(box.model()) {}
  explicit Adapter(QAbstractItemModel * model) : m_model(model) {}
  QVariant operator[](int i) { return m_model->index(i, 0); }
};

// point of use
for( auto i = 0; i < myQComboBox->count(); i++ )
{
    result[i] = Adapter(myQComboBox)[i];
}

A similar adapter could provide you with iterators.

Answer 2

You can retrieve items data using the combo box's model. Here is an example, how I would do that:

QComboBox combo;
combo.addItem("Item 1");

QAbstractItemModel *model = combo.model();
QModelIndex idx = model->index(0, 0); // Refers to the first item
QString item = model->data(idx).toString(); // Returns 'Item 1'

To access the second and further items of the combo box, just change the row number in index() function call:

QModelIndex idx = model->index(0, 0);
                the row number ^

I am not aware of any iterators based API for combo boxes so far, but you can use all the strength of QAbstractItemModel.