Clear all TreeView nodes

[Sergey Vdovin]

Hello.

How to clear all the nodes in TreeView widget? I made up one way but there're a question that confuses me.

tree_view_sandbox.py

from kivy.app import App
from kivy.uix.treeview import TreeViewLabel
from kivy.uix.floatlayout import FloatLayout

class main_window(FloatLayout):
 
 def tree_populate(self, tv):
 tv.add_node(TreeViewLabel(text='My first item'))
 tv.add_node(TreeViewLabel(text='My second item'))
 tv.add_node(TreeViewLabel(text='My third item'))
 tv.add_node(TreeViewLabel(text='My fourth item'))
 tv.add_node(TreeViewLabel(text='My fifth item'))
 tv.add_node(TreeViewLabel(text='My sixth item'))
 tv.add_node(TreeViewLabel(text='My seventh item'))
 tv.add_node(TreeViewLabel(text='My eighth item'))
 
 def tree_clear(self, tv):
 while tv.root.nodes: #for some reason, kivy clears only part of nodes with just FOR loop
 for node in tv.root.nodes:
 tv.remove_node(node)


class tree_view_sandboxApp(App):
 title = "TreeView Sandbox"
 
 def build(self):
 return main_window()


if __name__ == '__main__':
 tree_view_sandboxApp().run()

tree_view_sandbox.kv

<main_window>:
 BoxLayout:
 orientation: 'vertical'
 size_hint: None, None
 width: 500
 height: 400
 top: root.top
 
 BoxLayout:
 orientation: 'horizontal'
 size_hint: 1, None
 height: 40
 
 Button:
 text: 'Populate'
 size_hint: 0.5, 1
 on_press: root.tree_populate(tv)
 Button:
 text: 'Clear'
 size_hint: 0.5, 1
 on_press: root.tree_clear(tv)
 
 TreeView:
 id: tv
 root_options: dict(text='Sandbox tree root')

This code works. When I press "Populate" button, Tree appears. Then, I press "Clear" button, all the nodes disappear. BUT! I expect that code should be:

def tree_clear(self, tv):
 for node in tv.root.nodes:
 tv.remove_node(node)

In this case, when I press "Clear" button, nodes disappear partially. First pressing - "Second", "Fourth", "Sixth" and "Eight" nodes are still alive. Second pressing - "Fourth" and "Eight" here. Third pressing - "Eight" remains. Fourth pressing - there're no nodes.

P.S. I get exactly the same result If I use the builtin method iterate_all_nodes():

def tree_clear(self, tv):
 for node in tv.iterate_all_nodes():
 tv.remove_node(node)

def tree_clear(self, tv):
 while tv.root.nodes:
 for node in tv.iterate_all_nodes():
 tv.remove_node(node)

Why does it works in that manner?

[ZenCODE]

Why not tv.clear_widgets()?

[Sergey Vdovin]

This is not the same. tv.clear_widgets() delete the whole Tree including ROOT. Furthermore, If I then press "Populate", program NOT REFRESHes data, it ADDs new data and display it again. Like If you remove a paper, write new words and give it back to a person. My goal is to update data.

воскресенье, 28 октября 2018 г., 21:35:56 UTC+3 пользователь ZenCODE написал:

Why not tv.clear_widgets()?