Accessing a the click() slot of a button generated during runtime - Qt Creator

Question

I have a GUI project in Qt Creator that functions as a shopping list. I am using a QLineEdit to add items to a QTableWidget. The user types something in, presses the QPushButton. The slot then adds a new row to the QTableWidget with the input, in the first column, and a new QPushButton in the second column. I then want the user to be able to press the button and have it clear that row, but I don't know how to access that slot, or sender (I'm not sure the proper term.) Here is the code so far. itemList is my QTableWidget, itemInput is the QLineEdit.

void MainWindow::on_btnAddItem_clicked()
{
    ui->itemList->insertRow(ui->itemList->rowCount());
    ui->itemList->setItem((ui->itemList->rowCount())-1,0,new QTableWidgetItem(ui->itemInput->text()));
    QPushButton *clear = new QPushButton("Clear",this);
    ui->itemList->setIndexWidget(ui->itemList->model()->index(ui->itemList->rowCount()-1, 1), clear);
    ui->itemInput->clear();
}

Here is when the program is initially run. Once they click the button, it runs on_btnAddItem_clicked()

Then it looks like this, and I want to make the clear button remove the row it is a part of.

Do I need to create a new slot? Any help?

Do I need to create a new slot? Yes if you don't have one. I see you are creating the new button but not connecting its clicked() signal to a slot in MainWindow. Also don't use the on_ naming convention for the new slot you create since this will not be an automatic connection. — drescherjm
@drescherjm, from my understanding, he/she is trying to connect the clicked() signal to a certain slot of the QTableWidget (or its model or delegate?) with a corresponding QTableWidgetItem as input parameter so that it is possible to edit/erase the content of that QTableWidgetItem. The signal clicked() is only able to pass bool as parameter, so how would they access which row to erase. Does it sound right ? — vicrucann
No no, the clicked() signal I already have adds the user input to the table along with a new PushButton in the same row. I then want the user to be able to push the button and have it clear the row. That way, they can delete entries from the table. But I cannot pre-create the rows and buttons because I don't know how many entries a user will enter, so I'm not sure how to make a button do something if it doesn't exist until the program is running. — Kenta
@Kenta, I referred to the signal clicked() of QPushButton that you create dynamically which is called "Clear" on your screenshot. Does it make sense now? — vicrucann

Apin Apin · Accepted Answer · 2016-03-21T10:47:37

You will need to make your own button class and inherit QPushButton. Something like this :

class MyButton : public QPushButton {
    public:
    MyButton();
    QTableWidgetItem *titem;
}

And here you MainWindow :

void MainWindow::on_btnAddItem_clicked()
{
    ui->itemList->insertRow(ui->itemList->rowCount());
    ui->itemList->setItem((ui->itemList->rowCount())-1,0,new QTableWidgetItem(ui->itemInput->text()));
    MyButton *clear = new MyButton("Clear",this);
    clear->titem = ui->itemList->item(ui->itemList->rowCount()-1, 0);
    connect(clear, SIGNAL(clicked()), SLOT(on_btnClear_Clicked()));
    ui->itemList->setIndexWidget(ui->itemList->model()->index(ui->itemList->rowCount()-1, 1), clear);
    ui->itemInput->clear();
}

void MainWindow::on_btnClear_Clicked()
{
    MyButton *btn = (MyButton*)QObject::sender();
    ui->itemList->removeRow(btn->titem->row());
}

Please note, it is only step to do it.

Accessing a the click() slot of a button generated during runtime - Qt Creator

1 Answers