CODEWITHSUNDEEP
c++qtqt5qcombobox
Archit J
Archit J

Reputation: 150

Using Qt::UserRole and Qt::DisplayRole for Items in QComboBox

I am new to C++ Qt. I am trying to populate a QComboBox with values different than the values that need to be used. For example, QComboBox shows name of devices but on selection sends the mac address of that device. I have the data.

I tried using Qt::UserRole and Qt::DisplayRole but only the values mentioned in DisplayRole are used. I think I need to define the roles? If yes, then how? Any help regarding this?

QStandardItemModel *model = new QStandardItemModel(this);
int i = 0;
for (auto info : list)
{
    if (info.validateMACAddress())
    {
        memData->comboBox->addItem(info.getMacAddress().arg(i));
        memData->comboBox->setItemData(i, info.getDeviceName(), Qt::DisplayRole);
        memData->comboBox->setItemData(i, info.getMacAddress(), Qt::UserRole + 1);
        i++;
    }
}
memData->comboBox->setModel(model);

Upvotes: 2

Views: 3274

Answers (2)

Simon
Simon

Reputation: 1590

You can use the currentIndexChanged signal

One option is to use labmda.

connect(memData->comboBox, QOverload<int>::of(&QComboBox::currentIndexChanged),
    [=](int index)
    { 
         // get mac address
         auto oMacAddress = memData->comboBox->itemData(index, Qt::UserRole +1);

    });

Or add slot to your class

 connect(memData->comboBox, QOverload<int>::of(&QComboBox::currentIndexChanged),
        this, &MyClass::HandleIndexChanged);

void MyClass::HandleIndexChanged(int index)
{
  // get mac address
  auto oMacAddress = memData->comboBox->itemData(index, Qt::UserRole +1);

}

Upvotes: 1

eyllanesc
eyllanesc

Reputation: 244122

It is not necessary to establish a model since QComboBox has an internal model. Also memData->comboBox->setItemData (i, text, Qt::DisplayRole); is equivalent to memData->comboBox->addItem(text); so just place one of them.

int i = 0;
for (auto info : list){
    if (info.validateMACAddress()){
        memData->comboBox->addItem(info.getMacAddress().arg(i));
        memData->comboBox->setItemData(i, info.getMacAddress(), Qt::UserRole + 1);
        i++;
    }
}

And to get the mac you should use the currentData() method in the slot:

// Slot:

auto mac = memData->comboBox->currentData(Qt::UserRole + 1);

Upvotes: 3

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