Multiple AutoCompleters for the same LineEdit box

Core2

In the animalsearch.h file i have the following:

namespace Ui {
class AnimalSearch;
}
class AnimalSearch : public QDialog 
{
     Q_OBJECT
public:
   stuff

private slots:
    stuff

signals: 
    stuff

private:
    QCompleter *TurtleCompleter;
    QCompleter *RabbitCompleter;
    QCompleter *DogCompleter;
    QCompleter *CatCompleter;

};

In the animalsearch.cpp i have the following:

#includes section

AnimalSearch::AnimalSearch(QWidget *parent):
    QDialog(parent),
    ui(new Ui::AnimalSearch)
{
    QStringList animals << "Turtle" << "Rabbit" << "Dog" << "Cat";
    ui->cmbFilter->addItems(animals);

    //section that collects the past animal search and stores in a model.  
    //Then I parse the data out of the model into individual QStringLists: 
   TurtleList, RabbitList, DogList, CatList;

    //Display each string list to make certain it is good. (the data looks good when i run.)
    qDebug() << TurtleList;
    qDebug() << RabbitList;
    qDebug() << DogList;
    qDebug() << CatList;

    //Then I build the completers
    TurtleCompleter = new QCompleter(TurtleList, this);
    ui->lineBy->setCompleter(TurtleList); //Default Completer

    RabbitCompleter = new QCompleter(RabbitList, this);

    DogCompleter = new QCompleter(DogList, this);

    CatCompleter = new QCompleter(CatList, this);
}

//Section about cmbFilter selection
void AnimalSearch::on_cmbFilter_currentIndexChanged()
{
    //for a test just neglect the current index and try to change the qcompleter being used by the lineBy box.
    qDebug() << "Does this print?";
    ui->lineBy->setCompleter(RabbitCompleter);
}

When the program is run it crashes after the qDebug() << "Does this print?"

mrjj

Hi
where is your setupUI() ?

Core2

@mrjj

The animalsearch ui is launched when a button is clicked on the parent ui. Does that answer the question? I'm not a seasoned Qt user so I may have not understood your question. Thanks for your time.

mrjj

Hi
sorry if not clear.
Normally when using UI files, there is a call to a function that creates the objects.
MainWindow::MainWindow(QWidget* parent) :
QMainWindow(parent),
ui(new Ui::MainWindow) {
ui->setupUi(this); <<<< --- std.

I could not see in your code so i did wonder. but if it runs it must be there :)

Core2

@mrjj
Ok yeah i see that in the mainview.cpp which launches the animalsearch ui. It's exactly as you posted.

mrjj

@Core2
Ok, but i assume you have the same for AnimalSearch or else anything you have in the UI files
will be dangling pointers.

You call setupUI manually from mainwindow or something like that ?

Can you show how you init AnimalSearch ?
if you never call setup, the line ui->cmbFilter->xxx would crash
so since it seems something else, i guess its ok, just not standard way?

Core2

@mrjj

from mainview.cpp

//Needs better commenting.
void MainView::on_btnAnimalSearch_clicked()
{
    AnimalSearch animalsearch;
    animalsearch.setModal(true);
    connect(&animalsearch, SIGNAL(sendData(QString)), this, SLOT(printData(QString)));
    animalsearch.exec();
}

mrjj

@Core2
ok. odd. but dialog works and the widgets in the UI are shown so
that part does work?
I mean, there is no issues with
ui->cmbFilter->addItems(animals); ?
That would really crash if dangling pointer.

Core2

@mrjj

yeah that part works and has been for some time. now that i introduced multiple Qcompleters and trying to assign a Qcompleter depending on cmbFilter state is when things started failing. As you can see from the example code above I assign a default of TurtleQcompleter, and then in the section of code:

void AnimalSearch::on_cmbFilter_currentIndexChanged()

runs when the animalsearch ui is started, even though I don't change the cmbFilter, and I try for a test to set the Qcompleter to Rabbit Qcompleter from the earlier assignment of TurtleQcompleter.

mrjj

Hi
yes it will fire such signal when current item/index is set.
Also when done in code as doc states
http://doc.qt.io/qt-5/qcombobox.html#currentIndexChanged
So that is pretty normal.

Core2

@mrjj

Ok good to know. I will remove my line where I assign a default Qcompleter, and allow this section of code to make the first assignment.

Now i just have to figure out after I make the Qcompleters why i can't assign a different Qcompleter from elsewhere in the code.

Thanks again for your time.

SGaist

Can you show the backtrace from your crash ?

Core2

@SGaist

backtrace? I don't know what that is.

SGaist

It's the list of functions called shown by the debugger when the application crashes.

mrjj

Hi
What you mean by
"why i can't assign a different Qcompleter from elsewhere in the code" ?
In what why does it not work ?

Core2

@SGaist

I think by watching this video by VoidRealms I will be able to gather this info.
https://www.youtube.com/watch?v=B7UsWtyhXh4

Core2

@mrjj

I mean that in the animalsearch ui(new Ui::AnimalSearch) I create the Qcompleters from data i collect from sql into a model that i parse to QstringLists, then in a cmbFilter slot I assign the Qcompleter to the lineBy box.

mrjj

@Core2
Ok. that should just work.
I tried the Qt completer sample and there seems to be no issues switching completer.

Core2

@mrjj

Interesting. I may set up a test project where i set up a basic program to do this one thing with a cmbFilter, and a LineEdit. Until then I think I go the debugger working and am getting good info. I'm about to respond to SGaist.

mrjj

@Core2
Ok. good plan. The call stack will show what happened up till the crash.
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