comboBox->additem() crash application..

[TheCipo76]

Hi,
i've populated from database n.1 comboBox and all is OK

if i click on Annulla pushbutton (this is the code):

void inserisciarticolo::on_pushButton_Annulla_clicked()
{
    // ANNULLA
    if (aDatabase.open()) {
        aDatabase.close();
    }
    close();
}

and try to re-load the dialog (from application menu)

after first record of database additem() crashes the application

if i comment the additem() all works

this is the code i've used to load the comboBox data:

QSqlQuery cl;
    cl.prepare("Select RAGSOC from CLIENTI order by RAGSOC ASC");
    ui->comboBox_Cliente->clear();
    if (cl.exec()) {
        cl.first();
        do {
            ui->comboBox_Cliente->addItem(cl.value(0).toString());
        } while (cl.next());
    }

ideas??

Thanks in advance.

[mrjj]

Hi
Check if
cl.first(); returns true before using it.

[TheCipo76]

@mrjj

if (cl.exec()) {
        msg.setText("QUI");
        msg.exec();
        cl.first();
        if (cl.first()) {
                msg.setText("OK");
                msg.exec();
        }
        do {
            ui->comboBox_Cliente->addItem(cl.value(0).toString());
        } while (cl.next());
    }

messagebox will appear with OK message

if i replace additem with messagebox all works correctly

[mrjj]

Hi
Super.
Try
QString test=cl.value(0).toString();
and see if it crash on that line instead.
else it must mean
ui->comboBox_Cliente is not valid pointer.

[VRonin]

I know this does not address your problem but it should solve it anyway. Replace all your code with:

QSqlQueryModel* queryModel = new QSqlQueryModel(this);
queryModel.setQuery(QStringLiteral("Select RAGSOC from CLIENTI order by RAGSOC ASC"));
if(dynamic_cast<QSqlQueryModel*>(ui->comboBox_Cliente->model()))
ui->comboBox_Cliente->model()->deleteLater();
ui->comboBox_Cliente->setModel(queryModel);

[TheCipo76]

@mrjj i've tried and crash on additem()..

comboBox is not a pointer .. i've create it with designer in the ui

[TheCipo76]

@VRonin it will crash however

[Cobra91151]

@TheCipo76

Hi! Actually in designer it creates pointers, ui-> is the namespace, and comboBox_Cliente-> is a C++ pointer. What is the error message when it crashes?

[TheCipo76]

@Cobra91151

in application output :

18:45:34: The process was ended forcefully.
18:45:34: /Users/matteo/Desktop/C++/QT/EasyGest/build-EasyGest-Desktop_Qt_5_11_2_clang_64bit18-Release/EasyGest.app/Contents/MacOS/EasyGest crashed.

[VRonin]

in the constructor of your class, can you add QObject::connect(ui->comboBox_Cliente,&Qobject::destroyed,[]()->void{qDebug("Something exploded");});?

If you see the output it means you are deleting your ui before reusing it

[TheCipo76]

@VRonin said in comboBox->additem() crash application..:

QObject::connect(ui->comboBox_Cliente,&Qobject::destroyed,->void{qDebug("Something exploded");});

i don't understand where i have to put it..

in the .h file

after Q_OBJECT ??

[VRonin]

@VRonin said in comboBox->additem() crash application..:

in the constructor of your class

[TheCipo76]

@VRonin ok..

no output were showed

i've put it after

ui->setupUi(this);

in the dialog

[VRonin]

And it still crashes? did you set Qt::WA_DeleteOnClose?

[TheCipo76]

@VRonin No, i don't know what is it.. sorry but i'm new user of Qt

[VRonin]

One more try, add QObject::connect(this,&QObject::destroyed,[]()->void{qDebug("Something big exploded");}); and see if you have any output when you crash the application

[TheCipo76]

@VRonin said in comboBox->additem() crash application..:

QObject::connect(this,&QObject::destroyed,->void{qDebug("Something big exploded");});

no, i don't see any output..

[VRonin]

This is turning into a mistery now. Can you post the stack trace at the moment of crash?

[Cobra91151]

@TheCipo76

This crash happens after you addItem() to the ui->comboBox_Cliente?

Try to change the code to:

if (cl.exec()) {
    msg.setText("QUI");
    msg.exec();

    if (cl.first()) {
         msg.setText("OK");
         msg.exec();
    }

    do {
        ui->comboBox_Cliente->addItem(cl.value(0).toString());
    } while (cl.next());
 }

and check if it still crashes?

[JonB]

@TheCipo76

after first record of database additem() crashes the application

Has nobody yet asked you to run this in a debugger (e.g. from Qt Creator)? And give us the stacktrace? EDIT: Oh, @VRonin has 2 posts above. Please do so!