Combination Checklist + Input

Dash Python
1

Dash is cool. Thanks for making it.

Is there an easy way to have a checklist where ‘label’ is set by the value of an input? The only way I can think of seems a little clunky: to have separate dcc.checklist and dcc.input, then use app.callback to write the checklist label. Hopefully someone here has a more elegant idea.

2

That is indeed the right way to do it right now. Similar to the double dropdown example in the getting started guide: Dash Documentation & User Guide | Plotly

# -*- coding: utf-8 -*-
import dash
from dash.dependencies import Input, Output
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash(__name__)

all_options = {
    'America': ['New York City', 'San Francisco', 'Cincinnati'],
    'Canada': [u'Montréal', 'Toronto', 'Ottawa']
}
app.layout = html.Div([
    dcc.RadioItems(
        id='countries-dropdown',
        options=[{'label': k, 'value': k} for k in all_options.keys()],
        value='America'
    ),

    html.Hr(),

    dcc.RadioItems(id='cities-dropdown'),

    html.Hr(),

    html.Div(id='display-selected-values')
])

@app.callback(
    dash.dependencies.Output('cities-dropdown', 'options'),
    [dash.dependencies.Input('countries-dropdown', 'value')])
def set_cities_options(selected_country):
    return [{'label': i, 'value': i} for i in all_options[selected_country]]

@app.callback(
    dash.dependencies.Output('cities-dropdown', 'value'),
    [dash.dependencies.Input('cities-dropdown', 'options')])
def set_cities_value(available_options):
    return available_options[0]['value']

@app.callback(
    dash.dependencies.Output('display-selected-values', 'children'),
    [dash.dependencies.Input('countries-dropdown', 'value'),
     dash.dependencies.Input('cities-dropdown', 'value')])
def set_display_children(selected_country, selected_city):
    return u'{} is a city in {}'.format(
        selected_city, selected_country,
    )

if __name__ == '__main__':
    app.run_server(debug=True)

3

Hey @chriddyp, I’ve modified this example to use the same idea with a dcc.Checklist and it seems to fail with a JSON error. Do you have any ideas why the below will not work?

import dash
from dash.dependencies import Input, Output
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash(__name__)

all_options = {
    'America': ['New York City', 'San Francisco', 'Cincinnati'],
    'Canada': [u'Montréal', 'Toronto', 'Ottawa']
}
app.layout = html.Div([
    dcc.RadioItems(
        id='countries-dropdown',
        options=[{'label': k, 'value': k} for k in all_options.keys()],
        value='America'
    ),

    html.Hr(),

    dcc.Checklist(id='cities-dropdown'),

    html.Hr(),

    html.Div(id='display-selected-values')
])

@app.callback(
    dash.dependencies.Output('cities-dropdown', 'options'),
    [dash.dependencies.Input('countries-dropdown', 'value')])
def set_cities_options(selected_country):
    return [{'label': i, 'value': i} for i in all_options[selected_country]]

@app.callback(
    dash.dependencies.Output('cities-dropdown', 'values'),
    [dash.dependencies.Input('cities-dropdown', 'options')])
def set_cities_value(available_options):
    return available_options[0]['value']

@app.callback(
    dash.dependencies.Output('display-selected-values', 'children'),
    [dash.dependencies.Input('countries-dropdown', 'value'),
     dash.dependencies.Input('cities-dropdown', 'values')])
def set_display_children(selected_country, selected_city):
    return u'{} is a city in {}'.format(
        selected_city, selected_country,
    )

if __name__ == '__main__':
    app.run_server(debug=True)