Sequential qcombobox with qsqlquerymodel

[Daniziz]

Hi all,

I have an app with 3 qComboBox i would like to be linked.

My first combo is "hardcoded" (it is a yes/no combo).

ui->FirstCombo->addItem("YES");
ui->FirstCombo->addItem("NO");

I want my second combo as a result of a query using data from first combo like this:

void MainWindow::on_firstCombo_currentIndexChanged(const QString &firstCombotext)
{
    QString qry = "SELECT fieldA FROM tableA WHERE fieldB = firstCombotext"
    model->setQuery(qry);
    ui->SecondCombo->setModel(asociacion);
}

This works fine, my problem is with my third combo, which uses data from first and second combo when user selects one value on second combo:

void MainWindow::on_SecondCombo_currentIndexChanged(const QString &secondComboText)
{
    QString qry = "SELECT fieldA FROM tableB WHERE fieldB = secondComboText AND fieldC ="+ ui->FirstCombo->currenttext();
    model->setQuery(qry);
    ui->ThirdCombo->setModel(model);
}

Here I screw me my combos, and If I debug it, with every change I do on first combo, it makes three iterations on signal "on_SecondCombo_currentIndexChanged".

Is there any way to do it?

Regards,

[Daniziz]

Hi @JonB

Thats it... im sooooooo dumb.

I was pointing to the same combo, now it works!!

I've changed

ui->nAsociacionComboBox->setModel(direcciones);

to

ui->nDireccionesComboBox->setModel(direcciones); //Third combo!

Now it's working fine!!!

Thank you very much.

[JonB]

@Daniziz

Here I screw me my combos

That sounds bad :)

Goodness knows what your behaviour is. In combo #2:

    model->setQuery(qry);
    ui->SecondCombo->setModel(asociacion);

You set model's query, but you set the combo's model to asociacion. Doesn't look right.

In combo #3:

    model->setQuery(qry);
    ui->ThirdCombo->setModel(model);

Here you do set the combo's model to model. But is that the same model as you are using for combo #2?

Not sure how much of the code you show is your actual code.... If you are really using literally WHERE fieldB = firstCombotext, WHERE fieldB = secondComboText neither of those will work....

[Daniziz]

Hi @JonB

I was trying to post as pseudocode to be more clear... bad idea... my real code is this one:

 ui->nClienteComboBox->addItem("YES");
 ui->nClienteComboBox->addItem("NO");

void MainWindow::on_nClienteComboBox_currentIndexChanged(const QString &arg1)
{
    //Modelo SQL para obtener los compos de base de datos
    QSqlQuery qry_navision(QSqlDatabase::database("navision"));
    QSqlQueryModel *asociacion = new QSqlQueryModel();
    QString qry = "SELECT DISTINCT [Nombre Comercial] FROM Direcciones WHERE Cliente = (SELECT Contador FROM Clientes WHERE [Nombre Fiscal] = '"+arg1+"') ";

    //Cargamos el combo proyectos de BBDD
    qry_navision.prepare(qry);
    asociacion->setQuery(qry_navision);
    ui->nAsociacionComboBox->setModel(asociacion);
}


void MainWindow::on_nAsociacionComboBox_currentIndexChanged(const QString &arg2)
{
    QSqlQuery qry_navision1(QSqlDatabase::database("navision"));
    QSqlQueryModel *direcciones = new QSqlQueryModel();
    QString qry = "SELECT DISTINCT Domicilio FROM Direcciones WHERE "
                  "Cliente = (SELECT Contador FROM Clientes WHERE [Nombre Fiscal] = '"
                  +ui->nClienteComboBox->currentText()+"') AND [Nombre Comercial] = '"
                  +arg2+"'";

    //Cargamos el combo proyectos de BBDD
    qry_navision1.prepare(qry);
    direcciones->setQuery(qry_navision1);
    ui->nAsociacionComboBox->setModel(direcciones);
}

As you can see, i dont use same var names for models, and SQL syntax is correct... (I've launched the queries on the database ok).

Sorry for the previous one :)

Regards,

[JonB]

@Daniziz

it makes three iterations on signal "on_SecondCombo_currentIndexChanged".

Trying to guess: when you change selection in nClienteComboBox it changes the model of nAsociacionComboBox, which is not too bad I guess. But while you are inside on_nAsociacionComboBox_currentIndexChanged() you change the model it itself is currently using (I don't know what you're trying to achieve). I don't think that's a good idea at all.... This could well be causing your "cascading" calls, e.g. among other things, won't this likely change nAsociacionComboBox's current index and cause re-entry?

On a separate note: You seem to be leaking a QSqlQueryModel on each callback. I would not expect code to change models here at all. Maybe re-execute a query, but not change the whole model.

[Daniziz]

Hi @JonB,

I want my first combo to act like a filter for the values of the second one.

Then, when you select a value from the second, it acts like a filter for the third one, but combined with the value of the first combo.

• User select YES on First combo.
• The results on the second are halved due to first one. User selects XXXX
• The list of the third combo is filtered by YES and XXX.

How can I do that?

Regards,

[JonB]

@Daniziz
Well you would do that just like you've written in your 3 bullet points. Something like:

• Selecting in combo #1 causes both combo #2 & combo #3 values to be recalculated. (Or, you may be saying you don't want #3 to be re-evaluated immediately from #1, you want to wait for user to pick in #2 too, I don't know.)
• Selecting in combo #2 causes just combo #3 values to be recalculated (based in what has just been picked in #2 plus whatever is currently picked in #1).

I think that's what you're saying you want.

But you have:

void MainWindow::on_nAsociacionComboBox_currentIndexChanged(const QString &arg2)
...
    ui->nAsociacionComboBox->setModel(direcciones);
    

so you are making choosing in combo #2 actually re-evaluate/change what is in combo #2, and from inside combo #2's own slot. That does not sound right, and could well cause re-entry.

[Daniziz]

Hi @JonB

Thats it... im sooooooo dumb.

I was pointing to the same combo, now it works!!

I've changed

ui->nAsociacionComboBox->setModel(direcciones);

to

ui->nDireccionesComboBox->setModel(direcciones); //Third combo!

Now it's working fine!!!

Thank you very much.