Issue of QComboBox:currentIndexChanged() and Model

[mbnoimi]

Hello,

QComboBox doesn't show currentIndex correctly after calling any method from its model; How can I fix this issue?

[code]Requests::Requests(QWidget *parent) :
QDialog(parent),
ui(new Ui::Requests)
{
ui->setupUi(this);
ui->comboBox_category->setModel(model_labCategoryList());
ui->comboBox_category->setModelColumn(1);
}

QSqlQueryModel *Requests::model_labCategoryList() const
{
_model_labCategoryList->setQuery(query_selectAllCategories);
return _model_labCategoryList;
}

void Requests::on_comboBox_category_currentIndexChanged(int index)
{
// current index of comboBox_category disappear here
// When I comment the line below the GUI works fine
int categoryId = _db->model_labCategoryList()->record(index).value("id").toInt();
ui->spinBox->setValue(categoryId);
}[/code]

NOTE: on_comboBox_category_currentIndexChanged() works fine but the GUI doesn't show correctly!

[mbnoimi]

When I added this debug line:
[code]void Requests::on_comboBox_category_currentIndexChanged(int index)
{
// current index of comboBox_category disappear here
// When I comment the line below the GUI works fine
int categoryId = _db->model_labCategoryList()->record(index).value("id").toInt();
ui->spinBox->setValue(categoryId);
qDebug() << "categoryId" << categoryId;
}[/code]

I got:
[code]categoryId 0
categoryId 1[/code]

Really strange!!!

[mbnoimi]

I tried to use the following although the debug result is OK but the GUI still not working fine!

[code] void Requests::on_comboBox_category_currentIndexChanged(int index)
{
if (index > -1) {
// current index of comboBox_category disappear here
// When I comment the line below the GUI works fine
int categoryId = _db->model_labCategoryList()->record(index).value("id").toInt();
ui->spinBox->setValue(categoryId);
qDebug() << "categoryId" << categoryId;
}
}
[/code]

Debug:
[code]categoryId 1[/code]