Solved QComboBox keep currentText after model update

[Oshio]

I've a couple of QComboBox widgets populated from a QStringListModel.

Every time I update the model, the QComboBox reset to the first index.

Example:

• Model is {1,2};
• Select 2 in the QComboBox;
• Add 3 to model. Now model is {1,2,3};
• Current text changes to 1;

Snippet Code:

MainWindow::MainWindow(QWidget *parent)
  : QMainWindow(parent)
  , ui(new Ui::MainWindow)
{
  ui->setupUi(this);

  m_model.setStringList({"1","2"});

  ui->comboBox->setModel(&model);
}

void MainWindow::on_pushButton_clicked()
{
  QStringList newList = {"1","2","3"};
  m_model.setStringList(newList);
}

How to avoid the index from being reset?

[Oshio]

The problem arises from the usage of the method m_model.setStringList(). The latter always clear the previous data, hence the index always reset upon its call.

Solution:

Use m_model.setStringList() only in the constructor to init the model.

After that manually insert the row on the model and set the data for the respective row. This can be achieved with a simple modification in the slot method.

MainWindow::MainWindow(QWidget *parent)
  : QMainWindow(parent)
  , ui(new Ui::MainWindow)
{
  ui->setupUi(this);

  m_model.setStringList({"1","2"});

  ui->comboBox->setModel(&model);
}

void MainWindow::on_pushButton_clicked()
{
  m_model.insertRow(model.rowCount());
  m_model.setData(model.index(model.rowCount()-1), "3");
}

In the example above, "3" is appended to the list model without changing the current index from the QComboBox.