Deleting rows from QTableWidget

Jabik

Hello guys, can someone help me?
I am trying to delete row from a QTableWidget.
So, i have:

food_table = new QTableWidget(1, 2);

then, it connects to a slot

connect(food_table, SIGNAL(cellChanged(int,int)), this, SLOT(checkTheCells(int,int)));

slot code:

void InsertNewEatingDialog::checkTheCells(int changed_row, int changed_column)
{
    int total_rows{food_table->rowCount()};
    if(rowIsEmpty(changed_row) && total_rows > 1) food_table->removeRow(changed_row);
    if(tableIsFull()) food_table->insertRow(total_rows);
}

rowIsEmpty() and tableIsFull() are just bool member functions.
And it all works, but when the code running, when the row was deleted, i receive a message in qt developer's terminal, which says:

QAbstractItemView::commitData called with an editor that does not belong to this view

and then the program continues to run normally until the next row deleting. Then that message again.
I noticed that if I replace 1 with 2 in the line

if(rowIsEmpty(changed_row) && total_rows > 1) food_table->removeRow(changed_row);

it works without any messages.
Can someone explain me the cause of the error and a possible solution?

SGaist

Hi and welcome to devnet,

Any chances you have an editor opened in the row you are trying to delete ?
How are you editing your cells ?
How are you deleting your cells ?

Jabik

@SGaist said in Deleting rows from QTableWidget:

welcome to devnet,

thx

@SGaist said in Deleting rows from QTableWidget:

How are you editing your cells ?

standard editing with left click (or dbl click) and entering the value, then "enter", or just click somewhere outside the editing cell

@SGaist said in Deleting rows from QTableWidget:

How are you deleting your cells ?
i'm dbl clicking the cell, then just "delete". then "enter" or click somewhere outside the cell. I understand, that this action just makes QTableWidgetItem's text empty and nothing more.

but any of these actions emits signal cellChanged(int, int).
this signal is connected with my own slot checkTheCells(int, int);

then, inside the signal i'm checking if row is empty. Empty means, that either:

every cell item is empty

QTableWidgetItem* item; 
if(!item){...}

-or

item->text().size() == 0

if all cells in a row are empty, then i'm removing the whole row, because i don't need it

if(rowIsEmpty(changed_row) && total_rows > 1) food_table->removeRow(changed_row);

that's all

Christian Ehrlicher

The problem is that the editor is not yet closed when cellChanged()/dataChanged() is emitted and you're killing the row where the editor lives in. Use a Qt::QueuedConnection:

int main(int argc, char* argv[])
{
    QApplication a(argc, argv);
    QTableWidget tw(10, 10);
    QObject::connect(&tw, &QTableWidget::cellChanged, &tw, [&](int row, int) {
        tw.removeRow(row);
        }, Qt::QueuedConnection);
    tw.show();
    return a.exec();
}

Jabik

@Christian-Ehrlicher
Yeah, that works perfectly.
But to understand, what is "the editor"? Is it an object inside QT library, or is it an external process in OS?
How can I interact with it?
Or just, where to read about it?

Christian Ehrlicher

@Jabik said in Deleting rows from QTableWidget:

But to understand, what is "the editor"? Is it an object inside QT library, or is it an external process in OS?

When you edit a cell, an editor is created so you can enter the new value.
See https://doc.qt.io/qt-6/model-view-programming.html#delegate-classes

Jabik

@Christian-Ehrlicher
Ok, thank you, i'll read it