kivy/python : bind event when node is selected in treeview

Question

test.py

from kivy.uix.screenmanager import Screen
from kivy.app import App
from kivy.lang import Builder
from kivy.core.window import Window
from kivy.uix.popup import Popup
from kivy.uix.treeview import TreeView, TreeViewLabel, TreeViewNode
from kivy.uix.label import Label
from kivy.properties import ObjectProperty



Window.size = (700, 530)


def populate_tree_view(tree_view, parent, node):
    if parent is None:
        tree_node = tree_view.add_node(TreeViewLabel(text=node['node_id'],
                                                     is_open=True))
    else:
        tree_node = tree_view.add_node(TreeViewLabel(text=node['node_id'],
                                                     is_open=True), parent)

    for child_node in node['children']:
        populate_tree_view(tree_view, tree_node, child_node)


tree = []
rows = [(1, 'test1', 11), (2, 'test2', 2), (3, 'test3', 3), (4, 'test4', 4), (5, 'test5', 1)]
for r in rows:
    tree.append({'node_id': r[1], 'children': []})



class TreeViewLabel(Label, TreeViewNode):
    pass


class TreeviewGroup(Popup):
    treeview = ObjectProperty(None)
    tv = ObjectProperty(None)
    #ti = ObjectProperty()

    def __init__(self, **kwargs):
        super(TreeviewGroup, self).__init__(**kwargs)
        self.tv = TreeView(root_options=dict(text=""),
                       hide_root=False,
                       indent_level=4)
        for branch in tree:
            populate_tree_view(self.tv, None, branch)
        self.remove_widgets()
        self.treeview.add_widget(self.tv)

    def remove_widgets(self):
        for child in [child for child in self.treeview.children]:
            self.treeview.remove_widget(child)

        
    def select_node(self, node):
        '''Select a node in the tree.
                '''
        if node.no_selection:
            return
        if self._selected_node:
            self._selected_node.is_selected = False
        node.is_selected = True
        self._selected_node = node
        print(node)

class GroupScreen(Screen):
    groupName = ObjectProperty(None)
    popup = ObjectProperty(None)

    def display_groups(self, instance):
        if len(instance.text) > 0:
            if self.popup is None:
                self.popup = TreeviewGroup()
            #self.popup.filter(instance.text)
            self.popup.open()


    def select_node(self, node):
        '''Select a node in the tree.
                '''
        if node.no_selection:
            return
        if self._selected_node:
            self._selected_node.is_selected = False
        node.is_selected = True
        self._selected_node = node
        print(node)


class Group(App):
   
    #rows = [(1, 'test1', 111), (2, 'test2', 112), (3, 'test3', 113), (4, 'test4', 114)]
    def build(self):
        self.root = Builder.load_file('test.kv')
        return self.root


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

test.kv

#:kivy 1.10.0

<TreeViewLabel>:
    on_touch_down:
        app.root.stateName.text = self.text
        app.root.popup.dismiss()

<TreeviewGroup>:
    id: treeview
    treeview: treeview
    title: "Select City"
    size_hint: None, None
    size: 400, 400
    auto_dismiss: False

    BoxLayout
        orientation: "vertical"
        #TextInput:
            #id: ti
            #size_hint_y: .1
            #on_text: root.filter(self.text)
        BoxLayout:
            id: treeview
            #on_press: root.select_node(self.text)
        Button:
            size_hint: 1, 0.1
            text: "Close"
            on_release: root.dismiss()


<CustomLabel@Label>:
    text_size: self.size
    valign: "middle"
    padding_x: 5

<SingleLineTextInput@TextInput>:
    multiline: False

<GreenButton@Button>:
    background_color: 1, 1, 1, 1
    size_hint_y: None
    height: self.parent.height * 0.150

GroupScreen:
    stateName: stateName

    GridLayout:
        cols: 2
        padding : 30,30
        spacing: 10, 10
        row_default_height: '40dp'

        CustomLabel:
            text: 'Name'

        SingleLineTextInput:
            id: stateName
            on_text: root.display_groups(self)

        CustomLabel:
            text: 'Code'

        CustomLabel:
            text: '08'


        GreenButton:
            text: 'Ok'
            #on_press: root.insert_data(stateName.text, cityName.text, shortName.text , pinCode.text)


        GreenButton:
            text: 'Cancel'
            on_press: app.stop()

        Label:

        Label:

When i type anything in state name then a pop up open with treeview structure.

I want that when click on any node then it retrieve state code from database.And put value front of state code.at this time '08' is static value.database query is no issue for me but i dont know how to pass in a .py file after it put value in front of state code.And pop up should be close.

Answer 1

You can do this by adding a string property attribute to the Groupscreen class which will represent the statecode, then edit the select_node method to trigger the changes

...
from kivy.properties import ObjectProperty, StringProperty

...

class GroupScreen(Screen):
    groupName = ObjectProperty(None)
    popup = ObjectProperty(None)
    statecode = StringProperty('08')

...

    def select_node(self, node):
        '''Select a node in the tree.
            '''
        for r in rows:
            if node.text == r[1]:
                self.statecode = str(r[2])
                break

then in the kv:

<TreeViewLabel>:
    on_touch_down:
        app.root.stateName.text = self.text
        app.root.select_node(self)
        app.root.popup.dismiss()

...

GroupScreen:
    stateName: stateName

    GridLayout:
        cols: 2
        padding : 30,30
        spacing: 10, 10
        row_default_height: '40dp'

        CustomLabel:
            text: 'State Name'

        SingleLineTextInput:
            id: stateName
            on_text: root.display_groups(self)

        CustomLabel:
            text: 'State Code'

        CustomLabel:
            text: root.statecode

...