QTreeWidget

QTreeWidget

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# The QTreeWidget class provides a standard tree widget.

import sys

from PySide6.QtWidgets import (QApplication,
    QWidget, QVBoxLayout, QTreeWidget,
    QTreeWidgetItem, QLabel)


class Window(QWidget):
    
    def __init__(self):

        super().__init__()
        
        layout = QVBoxLayout()
        self.setLayout(layout)
        
        # 1 - Create the tree widget
        
        self.tree_widget = QTreeWidget()
        
        # 2 - Create the tree widget items and add them 
        #     to the tree widget
        #
        # apes parent is self.tree_widget which means 
        # apes is the root item
        #
        # ['Apes'] is the item text. It's a list with one element.
        # That's because a tree widget has one column by default.
        apes = QTreeWidgetItem(self.tree_widget, ['Apes'])
        
        # Add other items to the tree. The pattern is the same
        # as for the root item: (parent, text)
        # There are several other QTreeWidgetItem 
        # constructors as well.
        gibbons = QTreeWidgetItem(apes, ['Gibbons'])
        hominidae = QTreeWidgetItem(apes, ['Hominidae'])
        ponginae = QTreeWidgetItem(hominidae, ['Orangutans'])
        homininae = QTreeWidgetItem(hominidae, ['Homininae'])
        gorillinae = QTreeWidgetItem(homininae, ['Gorillas'])
        hominini = QTreeWidgetItem(homininae, ['Hominini'])
        panina = QTreeWidgetItem(hominini, ['Chimpanzees'])
        hominina = QTreeWidgetItem(hominini, ['Hominina'])
        
        # Add some event handling just for show. 
        self.tree_widget.currentItemChanged.connect(
            self.on_current_item_changed)
        
        self.label = QLabel()
        
        # 3 - Add the tree widget to the layout
        
        layout.addWidget(self.tree_widget)
        layout.addWidget(self.label)

    # The label will display currently selected item text.
    def on_current_item_changed(self, current, previous):
        self.label.setText(current.text(0))


if __name__ == '__main__':

    app = QApplication(sys.argv)

    main_window = Window()
    main_window.show()

    sys.exit(app.exec())

The QTreeWidget provides a standard tree widget. It uses a predefined item model - each tree node is represented with a QTreeWidgetItem instance. To use `QTreeWidget in your application

  1. Create a QTreeWidget object. It has only one constructor that optionally accepts the tree widget’s parent widget but we don’t set it here because adding a widget to a layout automatically sets the widget’s parent.

  2. Create QTreeWidgetItem objects and add them to the tree widget. Each tree node is represented by a QTreeWidgetItem object. If you set the QTreeWidget as its parent, like we do with the apes QTreeWidgetItem it becomes a root/top level item. If you set another QTreeWidgetItem as the parent that item becomes the parent and you use this parent-child relationship to form a tree structure that is displayed it the tree widget. We also use string lists like ['Gibbons'] to set the text to be displayed for each QTreeWidgetItem. QTreeWidget has one column by default but you can add more if you need.

  3. Add necessary slots, connect them with the appropriate QTreeWidget signals and add the tree widget to the window layout. In the example we set a label’s text to the current item text each time the tree widget current item changes.