Solved: QTabObject with QTableWidgetItem crash on delete

[SherifOmran]

Hello,

I have QTab object and in one tab, i have QTable on it. When the form unloads, it crashes.
The form is called from main as pointer

my h file
@
#ifndef REPORTWIN_H
#define REPORTWIN_H

#include <QDialog>
#include "tmain.h" //1
#include <QCloseEvent>

namespace Ui {
class reportwin;
}

class reportwin : public QDialog
{
Q_OBJECT

public:
explicit reportwin(QWidget *parent = 0);
~reportwin();
TMain *mainparentform; //2

protected:
void closeEvent(QCloseEvent *event); //3

private slots:

private:
Ui::reportwin *ui;
void preparegraph(int graphtype);
void initializeModel(QSqlTableModel *model);
QPointer <QTableWidget> table;
QHBoxLayout *layout;

};

#endif // REPORTWIN_H

@

here is how i create the table

@
layout=new QHBoxLayout(this);
table = new QTableWidget(rows, cols, this);
QStringList Header;
Header << " Date & Time" << " Number " << " Average Typing Speed " << " % Correct " << " % completed";
for (int r=0; r<rows; ++r)
{
for (int c = 0; c < cols; ++c)
{
QString character = Header.at(c);
table->setHorizontalHeaderItem(c, new QTableWidgetItem(character));

    QTableWidgetItem *dateitem = new QTableWidgetItem();
    dateitem->setText(practisedata.datestring.at(r));
    table->setItem( r, 0, dateitem );
    QTableWidgetItem *number = new QTableWidgetItem( practisedata.log1_practisetestnumber.at(r));
    table->setItem( r, 1, number )

}
}
table->setItemPrototype(table->item(rows -1, cols - 1));
table->setGeometry(QRect(55,90,660,300));
//table->show();
layout->addWidget(table);
this->ui->Training_tab1->setLayout(layout);

@

here is my main file
@
QPointer <reportwin> report = new reportwin(0);
report->mainparentform=this;

    //report->deleteLater();
    this->hide();
    report->exec();
    report->done(1);

// //delete report; // still not working, data still exist even after call
// QObjectCleanupHandler *cleaner=new QObjectCleanupHandler;
// cleaner->add(report);
// cleaner->deleteLater();

    qDebug() << " exit report" << report.isNull();

@

I tried delete later but it crashes, i tried the object cleaner but same result. I tried to delete the pointer but the same. I understand from the QT crash report that it has difficulty deleting the QTab or the QTableWidget

Any help is appreciated

[Mario84]

you should not call "delete report" since report is no pointer but a simple (stack) instance of QPointer. QPointer is an object that holds a pointer and behaves like one.
you could try to call "delete report->data();" but its probably better to use QSopedPointer. This class deletes the pointer it holds automatically in its destructor or when you call "reset()"

[SherifOmran]

I tried delete report->data(); but same result .. Can you show me how to use QScopedpointer? because i never used it before ..
thanks

[SherifOmran]

I use this now
@
QScopedPointer<reportwin> report(new reportwin(0));
@
I removed the delete phrase but then it crashes also
@
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 QtGui 0x0000000100cdcaf9 QTableModel::~QTableModel() + 41
1 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
2 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
3 QtGui 0x0000000100cd8a66 QTableWidget::~QTableWidget() + 38
4 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
5 QtGui 0x00000001007b39b9 QWidget::~QWidget() + 713
6 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
7 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
8 QtGui 0x0000000100bad8a9 QStackedWidget::~QStackedWidget() + 41
9 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
10 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
11 QtGui 0x0000000100bbac76 QTabWidget::~QTabWidget() + 38
12 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
13 QtGui 0x00000001007b39b9 QWidget::~QWidget() + 713
14 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
15 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
16 QtGui 0x0000000100bad8a9 QStackedWidget::~QStackedWidget() + 41
17 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
18 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
19 QtGui 0x0000000100bbac76 QTabWidget::~QTabWidget() + 38
20 QtCore 0x00000001004bc74f QObjectPrivate::deleteChildren() + 95
21 QtGui 0x00000001007b3ec9 QWidget::~QWidget() + 713
22 QtGui 0x0000000100b4af49 QFrame::~QFrame() + 41
@

[SherifOmran]

I found the mistake ..

there must be an empty unfilled row at the end of the table, otherwise it crashes
@
rows=rows+1;
@
@
table = new QTableWidget(rows, cols, this); // note to avoid crashing: there must be 1 empty row at the end
QStringList Header;
Header << " Date & Time" << " Number " << " Average Typing Speed " << " % Correct " << " % completed";
//QTableWidgetItem *dateitem[rows];
qDebug() << "rows=" << rows;
for (int r=0; r<rows-1; r++)
{
for (int c = 0; c <cols; c++)
{
QString character = Header.at(c);
table->setHorizontalHeaderItem(c, new QTableWidgetItem(character));
if (r<=rows-1)
{
QTableWidgetItem *dateitem = new QTableWidgetItem();
dateitem->setText(practisedata.datestring.at(r));
table->setItem( r, 0, dateitem );
QTableWidgetItem *number = new QTableWidgetItem( practisedata.log1_practisetestnumber.at(r));
}

}
}
table->setItemPrototype(table->item(rows -1, cols - 1));
table->setGeometry(QRect(55,90,660,300));
//table->show();
layout->addWidget(table);
this->ui->Training_tab1->setLayout(layout);

@