How to get a pointer to a specific widget when you know only its name?

[Ylvy]

I tried below but its returning null.

QMainWindow* window = QApplication::instance()->findChild<QMainWindow*>("AppClass");

QWidget* mainWindow = qApp->activeWindow(); work only if the window is active, would not help.

[JonB]

@Ylvy
Yes, if you want to find a top-level window, assuming your QMainWindow is such, and you are somewhere that does not have access to your QMainWindow* variable, walk (don't descend) QWidgetList QApplication::topLevelWidgets() for a QMainWindow*. Then use that for mainWindow->findChild<YourWidgetClass*>("SpecificWidgetObjectName");

I use this for debugging purposes. It may not be a sign of great design if your code really needs to find the main window for this purpose.

[jsulm]

@Ylvy Why do you need to get the pointer to your main window using the name? Main window does not necessarily have a parent.
Usually you call findChild from the parent (or anywhere higher in the hierarchy) of the widget.

[Ylvy]

@jsulm i'm trying to get a child from the QMainWindow, when i know only its name, but i'm trying to avoid passing/saving a pointer to the widget/QMainWindow.

[jsulm]

@Ylvy said in How to get a pointer to a specific widget when you know only its name?:

i'm trying to get a child from the QMainWindow

No, you don't.
You're trying to get pointer to QMainWindow instance using its name...

[JonB]

@Ylvy
As @jsulm has said. You are looking for a QMainWindow* named AppClass.

Main window does not necessarily have a parent.

An alternative call you can use is QWidgetList QApplication::topLevelWidgets() to examine or descend (findChild()) from.

[J.Hilk]

In addition to what the others said, are you sure, your instance actually has an objectName to look for ? A default object name is only done via QDesigner - plugin.

[Ylvy]

@J-Hilk Yes it does, so theres no other option than iterating the topLevelWidgets? im trying to get a pointer to the QMainWindow exclusively to get a pointer to a specific widget.

[JonB]

@Ylvy
Yes, if you want to find a top-level window, assuming your QMainWindow is such, and you are somewhere that does not have access to your QMainWindow* variable, walk (don't descend) QWidgetList QApplication::topLevelWidgets() for a QMainWindow*. Then use that for mainWindow->findChild<YourWidgetClass*>("SpecificWidgetObjectName");

I use this for debugging purposes. It may not be a sign of great design if your code really needs to find the main window for this purpose.