c++ - Access to QCheckBox from QWidgetAction

Question

Please consider the bellow codes:

QMenu* menu_ = new QMenu(this);
QWidgetAction *checkableAction = new QWidgetAction(menu_);

QCheckBox* checkBox1 = new QCheckBox("Sample1", menu_);
QCheckBox* checkBox2 = new QCheckBox("Sample2", menu_);

checkableAction->setDefaultWidget(checkBox1);
checkableAction->setDefaultWidget(checkBox2);

connect(checkableAction, &QWidgetAction::toggled, this, &MenuPushButton::onRec_triggered);

How can I access to QCheckBox features from QWidgetAction in onRec_triggered slot. I try the bellow codes but it does not works for me.

void MenuPushButton::onRec_triggered()
{
    for(QAction* action : menu_->actions())
        if(dynamic_cast<QCheckBox*>(action)->isChecked())
            qDebug()<<dynamic_cast<QCheckBox*>(action)->text();
}

question from:https://stackoverflow.com/questions/65600150/access-to-qcheckbox-from-qwidgetaction

Answer 1

This answer is based on code snippets provided by question. However i am not sure if the intention was to use "checkable" feature of base class QAction.

If you want to use the checkbox you set as QWidgetAction default widget to trigger your slot then you have to use connect(checkBox2, &QCheckBox::toggled, this, &MenuPushButton::onRec_triggered);. You can remove checkBox1 as it gets overridden by checkBox2 as default widget. In your slot you have to use a two step dynamic_cast. First dynamic_cast to check if action is of type QWidgetAction * and if that matches call defaultWidget() and try to dynamic_cast result to QCheckBox *. If that matches too then call text() method. Always check result of dynamic_cast before you call any method to avoid accessing a nullptr.

void MenuPushButton::onRec_triggered()
{
    for(QAction* action : menu_->actions()) {
        QWidgetAction *wa = dynamic_cast<QWidgetAction*>(action);
        if (wa) {
            QCheckBox *cb = dynamic_cast<QCheckBox*>(wa->defaultWidget());
            if (cb) {
                qDebug() << cb->text();
            }
        }
    }
}