QComboBox binding and returning selected value

rhonaldjr

Hi,

I have two questions (1) How do I bind a return value and text , returned by QSqlQueryModel to a combo box and (2) access the value of the selected item.

Below is my function to initialize the combobox

Binding QSqlQueryModel to QComboBox:

QSqlQuery sql("select id, title from coa_vals where parent_id is null;", db);
QSqlQueryModel *model = new QSqlQueryModel();
model->setQuery(sql);
ui->cbParent->setModel(model);
ui->cbParent->setModelColumn(1);
ui->cbParent->show();

Access the selected item's value.

Below is my code to get the selected value (suppose to be the ID column) from the combo box which doesn't work.

int row = index <0? ui->cbParent->currentIndex():index;
QModelIndex idx = ui->cbParent->model()->index(row, 0);
QVariant data = ui->cbParent->model()->data(idx);
int catid = data.toInt();
QString str = "select id, title, details from coa_values where parend_id = " + catid;

This sql always prints as below without the value of ID.

select id, title, details from coa_values where parent_id =

What did I miss? I have gone through almost all suggestions found about QComboBox and couldn't work. Alternative is to ditch the model, do manual binding with text and value.

SGaist

Hi,

Check the content of data, your toInt conversion might be failing.

rhonaldjr

Yep, made the below change (no idea why I didn't think earlier, could have saved 4 hours of my time) and it worked.

int row = index <0? ui->cbParent->currentIndex():index;
QModelIndex idx = ui->cbParent->model()->index(row, 0);
QVariant data = ui->cbParent->model()->data(idx);

QString str = "select id, title, details from coa_values where parend_id = " + data.toString();

Question: Why does the integer conversion fail? I have noticed this a lot.

SGaist

I didn't realise one thing, you where trying to add an int to string which will not to what you think/want. So the toInt was likely successful however you string building technique was wrong.

rhonaldjr

Yep, you made me think. the below works. Thanks a lot. Learning to program after years of hiatus. so am a bit rusty I guess.

QString str = "select id, title, details from coa_values where parend_id = ";
str.append(QString::number(data.toInt()));

So I guess, I should look to append rather than adding. Is there any other better way?

SGaist

There's no need for multiple conversion, your toString call was a correct manner to do that.

Otherwise, you can use QString::arg to build the string.

Karoluss96

@rhonaldjr said in QComboBox binding and returning selected value:

QSqlQueryModel()

Hi I've tried the same but in Python. What is cbParent?

JonB

@Karoluss96 said in QComboBox binding and returning selected value:

What is cbParent?

A QComboBox created in Designer.