Bug with setCurrentText on QComboBox

[Kolya]

Hi guys,

I would like to report a potential bug with method setCurrentText on QComboBox.
I am running Qt Creator 4.8.0 based on Qt 5.12.0 and using Windows 10.

I have the following implementation

mLocationComboBox = new QComboBox();
mLocationComboBox->setEditable(true);
mLocationComboBox->setMinimumContentsLength(70);
mLocationComboBox->setSizeAdjustPolicy(QComboBox::AdjustToMinimumContentsLength);
mLocationComboBox->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);

QStringList recentLocations;
recentLocations.append(QDir::homePath());

mLocationComboBox->insertItems(0, recentLocations);
mLocationComboBox->setCurrentIndex(0);

mLocationComboBox->addItem("Here1");
mLocationComboBox->addItem("Here2");
    
mLocationComboBox->setCurrentText("Here2");
auto currentText = mLocationComboBox->currentText(); // "Here2"
auto currentIndex = mLocationComboBox->currentIndex(); // 0

According to the documentation, currentIndex should be set to index of "Here2" that is 2, while it is set to 0.

Thank you!

[kshegunov]

Humor me for a second and run the event loop before you retrieve the index. Something like this:

mLocationComboBox->setCurrentText("Here2");

QCoreApplication::processEvents();

QString currentText = mLocationComboBox->currentText(); // "Here2"
int currentIndex = mLocationComboBox->currentIndex(); // 0

What do you get?

[J.Hilk]

@kshegunov 😲 don't encourage processEvents() calls!

mLocationComboBox->setCurrentText("Here2");

QMetaObject::InvokeMethod(this, [=]()->void{
    QString currentText = mLocationComboBox->currentText(); // "Here2"
    int currentIndex = mLocationComboBox->currentIndex(); // 0
}, Qt::QueuedConnection);

;-)

[Kolya]

@J-Hilk @kshegunov

guys, thank you for the prompt response!
I did check both suggestions and currentIndex equals to 0.

[J.Hilk]

@Kolya
well looking through the code example you posted, that behavior is not unexpected,

you set the combobox to be editable:

setEditable(true);

and according to the docu

The setter setCurrentText() simply calls setEditText() if the combo box is editable. Otherwise, if there is a matching text in the list, currentIndex is set to the corresponding index.

[Kolya]

@J-Hilk My bad - misinterpreted the documentation :-) Thank you for pointing out!

[SGaist]

Hi,

@Kolya said in Bug with setCurrentText on QComboBox:

According to the documentation, currentIndex should be set to index of "Here2" that is 2, while it is set to 0.

On a side note, you should not expect 2 but 1. In C++ the index are zero based.