Applying a layout to a QDockWidget in PyQt5

Question

I'm trying to create a docked interface in PyQt5, creating a BoxLayout contining my various widgets, and then applying this layout to the QDockWidget.

My approach so far has been:

self.layout = QtWidgets.QBoxLayout(2)
self.layout.addWidget(self.widget_one)
self.layout.addWidget(self.widget_two)
self.docked = QtWidgets.QDockWidget()
self.docked.setLayout(self.layout)
self.docked.show()

I'm currently getting an error as follows:

QWidget::setLayout: Attempting to set QLayout "" on QDockWidget "", 
which already has a layout

However, in my code above I can't see where I have added a layout previously, and can't find anything in the documentation to aid me in fixing this.

Where have I gone wrong in my approach?

Answer 1

QDockWidget already have a default layout so that generates this error, the correct thing is to add an empty widget and in that widget place the layout you want:

self.layout = QtWidgets.QBoxLayout(2)
self.layout.addWidget(self.widget_one)
self.layout.addWidget(self.widget_two)
self.docked = QtWidgets.QDockWidget()
self.dockedWidget = QtWidgets.QWidget()
self.docked.setWidget(self.dockedWidget)
self.dockedWidget.setLayout(self.layout)
self.docked.show()

Example:

class DockDemo(QMainWindow):
    def __init__(self, parent=None):
        super(DockDemo, self).__init__(parent)
        self.setCentralWidget(QTextEdit())

        self.docked = QDockWidget("Dockable", self)
        self.addDockWidget(Qt.LeftDockWidgetArea, self.docked)
        self.dockedWidget = QWidget(self)
        self.docked.setWidget(self.dockedWidget)
        self.setWindowTitle("Dock demo")
        self.dockedWidget.setLayout(QVBoxLayout())
        for i in range(5):
            self.dockedWidget.layout().addWidget(QPushButton("{}".format(i)))


if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    ex = DockDemo()
    ex.show()
    sys.exit(app.exec_())

Screenshot: