Setting CurrentIndex of comboBox with model

I have combobox with model like this

Code:

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cityModel = new QSqlTableModel(this);
cityModel->setTable("cities"); // (city_id, city_name)
cityModel->select();
comboBox_city->setModel(cityModel);
comboBox_city->setModelColumn(1);
comboBox_city->setCurrentIndex(0);

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I want to change current index of combobox to row of city_id has 15 value?
Please help me.

Following line doesnt work.

Code:

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comboBox_city->setCurrentIndex(comboBox_city->findData(query.value(rec.indexOf("city_id"))) );

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How about:

Code:

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for(int i=0;i<cityModel->rowCount();i++){
  QModelIndex index = cityModel->index(i, rec.indexOf("city_id"));
  if(index.data().toInt()==15){
    comboBox_city->setCurrentIndex(i);
    return;
  }
}

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