How to set my QTreeWidget expanded by default?-CodePudding

I have this QTreeWidget that I would like to be expanded by default. I have read this same question many times but the solutions aren't working for me. I tried the commands for the root of my tree: .ExpandAll() and .itemsExpandable() and for the children .setExpanded(True) with no success.

Here is the code of my test application:

import sys
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import (
    QApplication, QMainWindow, QWidget, 
    QTreeWidget, QTreeWidgetItem, QVBoxLayout
    )

# ----------------------------------------------------------------
unsorted_data = [
    ['att_0', 'a', 2020],
    ['att_0', 'a', 2015],
    ['att_2', 'b', 5300],
    ['att_0', 'a', 2100],
    ['att_1', 'b', 5013],
    ['att_1', 'c', 6500],
]

# Sort data
list_att = []
for elem in range(len(unsorted_data)) :
    att_ = unsorted_data[elem][0]
    if att_ not in list_att:
        list_att.append(att_)
list_att.sort()
n_att = len(list_att)

data = ['']*n_att
tree = ['']*n_att

list_a_number = []
list_b_number = []
list_c_number = []


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("My App")
        widget = QWidget()
        layout = QVBoxLayout()
        widget.setLayout(layout) 

        # QTreeWidget 
        main_tree = QTreeWidget()
        main_tree.setHeaderLabel('Test')
        # main_tree.itemsExpandable()   # NOT WORKING   
        # main_tree.expandAll()   # NOT WORKING   
        sublevel_1 = []
        
        for i, att in enumerate(list_att) :

            list_a_number.clear()
            list_b_number.clear()
            list_c_number.clear()

            # Create a dictionary
            for elem in range(len(unsorted_data)) :
                if unsorted_data[elem][0] == att :    
                    if unsorted_data[elem][1]== 'a' :
                        list_a_number.append(str(unsorted_data[elem][2]))
                    if unsorted_data[elem][1] == 'b' :
                        list_b_number.append(str(unsorted_data[elem][2]))
                    if unsorted_data[elem][1] == 'c' :
                        list_c_number.append(str(unsorted_data[elem][2]))
                    data[i] = {'a' : list_a_number, 'b' : list_b_number, 'c' : list_c_number}
            
            # Fill the Tree
            items = []
            att_id = list_att[i].split('\\')[-1]
            tree[i] = QTreeWidgetItem([att_id])
            tree[i].setExpanded(True)   # NOT WORKING   
            sublevel_1.append(tree[i])

            for key, values in data[i].items():
                item = QTreeWidgetItem([key])
                item.setCheckState(0, Qt.Checked)
                tree[i].addChild(item)
                
                for value in values :
                    child = QTreeWidgetItem([value])
                    child.setExpanded(True)   # NOT WORKING   
                    child.setCheckState(0, Qt.Checked)
                    item.addChild(child)
                    
                items.append(item)

        main_tree.insertTopLevelItems(0, sublevel_1)
        layout.addWidget(main_tree)

        self.setCentralWidget(widget)

# ------------------------------------------------------------------
app = QApplication(sys.argv)

window = MainWindow()
window.show()

sys.exit(app.exec())

CodePudding user response：

Try expandAll:

child.expandAll()

CodePudding user response：

You have to use expandAll after placing all the items in the QTreeWidget:

main_tree.insertTopLevelItems(0, sublevel_1)
main_tree.expandAll()
layout.addWidget(main_tree)

Note: One of the errors in your case is that you invoke setExpanded before the item is added to the QTreeWidget. remove useless setExpanded