Filtering in the QComboBox

[aliks-os]

I try to make a filtering in the popup list of QComboBox. Commonly is ready. But I have a crash during some consistency.
With the following error:
ASSERT failure in QVector<T>::remove: "index out of range", file ....\include/QtCore/../../src/corelib/tools/qvector.h, line 449

How to replicate.

1. Run application
2. Type in the combobox 'zzz'
3. Press Enter
4. Type any key

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QStringListModel>
#include <QSortFilterProxyModel>
#include <QCompleter>
#include <QComboBox>


namespace Ui {
class MainWindow;
}


class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    QCompleter *completer;
    QSortFilterProxyModel *proxyModel;
    QStringListModel *stringListModel;

private slots:
    void setFilterWildcard(const QString& value);

};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QLineEdit>


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    ui->comboBox->setEditable(true);


    QStringList Items;
    Items << "hi" << "bye";
    Items << "master" << "vessel";
    Items << "gun" << "rifle";
    Items << "handgun" << "atom";
    Items << "hello" << "manual";
    Items << "hillo" << "minual";

    stringListModel = new QStringListModel();
    stringListModel->setStringList(Items);

    proxyModel = new QSortFilterProxyModel;
    proxyModel->setSourceModel(stringListModel);
    proxyModel->setFilterCaseSensitivity(Qt::CaseInsensitive);
    ui->comboBox->setModel(proxyModel);


    auto completer = new QCompleter(this);
    completer->setCaseSensitivity(Qt::CaseInsensitive);
    completer->setModel(proxyModel);
    completer->setCompletionColumn(0);
    completer->setCompletionMode(QCompleter::UnfilteredPopupCompletion);
    ui->comboBox->setCompleter(completer);

    ui->comboBox->setCurrentIndex(-1);

    ui->comboBox->lineEdit()->setPlaceholderText("Some text");
    connect(ui->comboBox, SIGNAL(editTextChanged(const QString&)),
            this, SLOT(setFilterWildcard(const QString&)));

}

void MainWindow::setFilterWildcard(const QString &value)
{
    QStringList items = stringListModel->stringList();
        QString item;
        foreach(item, items) {
            if (item.indexOf(value) > -1) {
                proxyModel->setFilterFixedString(value);
                return;
            }
        }
}




MainWindow::~MainWindow()
{
    delete ui;
}

[aliks-os]

@aliks-os
sorry a lit bit correction

1. Run application
2. Type in the combobox 'zzz'
3. Press Enter
   3a) select 'zzz'
4. Type any key

[koahnig]

@aliks-os

Which OS are you on?

Out of curiosity I have created a new GUI app.
I had a freshly setup of Ubuntu 32 bit and an install of Qt 5.5.1 32 bit.
The MainWindow.cpp and include was changed to hold your code. For the MainWindow.ui I simply added a ComboBox with designer and left as is.

By performing the steps as iniially given and also the corrected sequence, I do not get a crash.

However, I can provoke a crash with
1 Run application
2 Type in the combobox 'zzz'
3 Press Enter
4 Mark 'zzz' to overwrite
5 Type any key

[aliks-os]

@koahnig said in Filtering in the QComboBox:

However, I can provoke a crash with
1 Run application
2 Type in the combobox 'zzz'
3 Press Enter
4 Mark 'zzz' to overwrite
5 Type any key

yes, you do all right. I am exactly get crash as you.
I am using Win10

[mrjj]

@koahnig
Hi
I did as you with default project.
Its does crash here on win 10 +Qt5.9 vs 2015

It seems to come from looping around in the list calling setFilterFixedString

However if i do.

void MainWindow::setFilterWildcard(const QString& value) {
  QStringList items = stringListModel->stringList();
 if (items.indexOf(value) > -1 )
    proxyModel->setFilterFixedString(value);
}

I cannot get it to crash anymore. Maybe it dont do exactly the same.

[koahnig]

@mrjj @aliks-os

Yes,it obviously comes from that loop.

When applying @mrjj changes it does not crash anymore. However, the functionality is not yet as expected.

I have tested on Ubuntu 32 bit with Qt 5.5.1 and win10 64 bit Qt 5.4.2 for MinGW.

[aliks-os]

I replace on the following

void MainWindow::setFilterWildcard(const QString &value)
{
    if (value == "")
        proxyModel->invalidate();
    else
        proxyModel->setFilterWildcard(value);
}