TreeSelect

Introduction

The TreeSelect widget in Supervisely is a user interface element that allows users to select items from a tree-like structure that can be useful when working with hierarchical data. The TreeSelect widget has event handlers that are triggered when items in the right lists are changed. This can be useful for applications that require dynamic change handling, such as showing data from the selected items.

Function signature

TreeSelect(
    items = None,
    multiple_select = False,
    flat = False,
    always_open = False,
    widget_id = None,
)

default

Parameters

Parameters	Type	Description
items	Optional[List[TreeSelect.Item]]	A list of TreeSelect.Item to be displayed in the widget.
multiple_select	bool	If True, multiple items can be selected. Default is False.
flat	bool	If True, selecting a parent item will not select its children. Default is False.
always_open	bool	If True, the tree will be opened when the widget is initialized.
widget_id	str	An optional ID for the widget.

items

Determine the list of TreeSelect.Item items, each of which must have a unique id and an optional label to be displayed in the widget. The children field is a list of TreeSelect.Item items that are children of the current item.

type: Optional[List[TreeSelect.Item]]

default value: None

Prepare the items:

items = [
    TreeSelect.Item(id="1", label="Item 1"),
    TreeSelect.Item(id="2", label="Item 2"),
    TreeSelect.Item(id="3", label="Item 3", children=[
        TreeSelect.Item(id="4", label="Item 3.1"),
        TreeSelect.Item(id="5", label="Item 3.2"),
    ]),
]

Initialize the widget with the items:

widget = TreeSelect(items=items)

multiple_select

If True, multiple items can be selected. Default is False.

type: bool

default value: False

Initialize the widget with multiple selection:

widget = TreeSelect(items=items, multiple_select=True)

multiple_select

flat

If True, selecting a parent item will not select its children. Default is False.

type: bool

default value: False

Initialize the widget with the flat option:

widget = TreeSelect(items=items, flat=True)

always_open

If True, the tree will be opened when the widget is initialized.

type: bool

default value: False

Initialize the widget with the always open option:

widget = TreeSelect(items=items, always_open=True)

widget_id

An optional ID for the widget.

type: str

default value: None

Initialize the widget with an ID:

widget = TreeSelect(items=items, widget_id="tree_select")

Methods and attributes

Methods and attributes	Description
set_items(items: List[TreeSelect.Item])	Set the items to be displayed in the widget (overrides current).
add_items(items: List[TreeSelect.Item])	Add items to the current list of items in the widget.
clear_items()	Clear all items from the widget.
get_selected()	Get the selected items in the widget.
set_selected(value: Union[List[TreeSelect.Item], TreeSelect.Item])	Set the selected items in the widget.

Mini app example

You can find this example in our GitHub repository:

supervisely-ecosystem/ui-widgets-demos/selection/021_tree_select/src/main.py

Import libraries

import os

import supervisely as sly
from dotenv import load_dotenv
from typing import List
from supervisely.app.widgets import Card, TreeSelect, Container, Text, Button, Flexbox

Init API client

First, we load environment variables with credentials and init API for communicating with Supervisely Instance:

load_dotenv("local.env")
load_dotenv(os.path.expanduser("~/supervisely.env"))
api = sly.Api()

Prepare the items

Prepare the items to be displayed in the TreeSelect widget:

domestic_animals = [
    TreeSelect.Item(
        id="cat",
        label="Cat",
        children=[
            TreeSelect.Item(id="siamese", label="Siamese"),
            TreeSelect.Item(id="persian", label="Persian"),
        ],
    ),
    TreeSelect.Item(
        id="dog",
        label="Dog",
        children=[
            TreeSelect.Item(id="bulldog", label="Bulldog"),
            TreeSelect.Item(id="beagle", label="Beagle"),
        ],
    ),
    TreeSelect.Item(id="cow", label="Cow"),
    TreeSelect.Item(id="sheep", label="Sheep"),
]

Initialize the TreeSelect widget

Let's initialize the TreeSelect widget without the items:

tree_select = TreeSelect(
    multiple_select=True,
    flat=True,
    always_open=False,
)

And then set the items:

tree_select.set_items(domestic_animals)

Dynamically add items

Let's prepare a new list of items, which will be added dynamically to the widget.

wild_animals = [
    TreeSelect.Item(
        id="mouse",
        label="Mouse",
        children=[
            TreeSelect.Item(id="field_mouse", label="Field mouse"),
            TreeSelect.Item(id="house_mouse", label="House mouse"),
        ],
    ),
    TreeSelect.Item(id="bird", label="Bird"),
]

And prepare a button, which will add the new items to the widget.

add_button = Button("Add wild animals")

We also need to set the handler for the button click event.

@add_button.click
def add_wild_animals():
    print("Adding wild animals")
    tree_select.add_items(wild_animals)

    add_button.disable()

Show selected items in UI

Now, let's create a button, which will show selected items in UI. And create a simple text widget to show the selected items.

show_selected_button = Button("Show selected")
selected_info = Text(status="info")
selected_info.hide()

Same as for the previous button, we need to set the handler for the click event.

@show_selected_button.click
def show_selected():
    print("Showing selected items")
    selected_items = tree_select.get_selected()
    if selected_items and isinstance(selected_items, list):
        labels = ", ".join([item.label for item in selected_items])
        text = "Selected items: {}".format(labels)

        selected_info.text = text
        selected_info.show()
    else:
        selected_info.hide()

Create an event handler for the TreeSelect widget

Now, let's create a event handler for the TreeSelect widget, when the value of the widget is changed.

value_changed_info = Text(status="info")
value_changed_info.hide()


@tree_select.value_changed
def new_items_selected(items: List[TreeSelect.Item]):
    print("Value changed")
    if items:
        # We're processing the event the same way as for the button click event.
        labels = ", ".join([item.label for item in items])
        text = "Value changed: {}".format(labels)

        # Setting the text to the widget and showing it.
        value_changed_info.text = text
        value_changed_info.show()
    else:
        value_changed_info.hide()

Create app layout

Prepare a layout for the app using Card widget with the content parameter and place widget that we've just created in the Container widget. Let's group our buttons in a Flexbox widget to make them look better.

buttons_flexbox = Flexbox(
    widgets=[add_button, show_selected_button],
)

card = Card(
    title="TreeSelect",
    content=Container(widgets=[buttons_flexbox, selected_info, value_changed_info, tree_select]),
)

layout = Container(widgets=[card])

Create an app using the layout

Create an app object with the layout parameter.

app = sly.Application(layout=layout)

mini_app