simple_use.rst

Simple usage

To use existing dash applications, first register them using the DjangoDash class. This replaces the Dash class from the dash package.

Taking a simple example inspired by the excellent getting started guide:

import dash
from dash import dcc, html

from django_plotly_dash import DjangoDash

app = DjangoDash('SimpleExample')   # replaces dash.Dash

app.layout = html.Div([
    dcc.RadioItems(
        id='dropdown-color',
        options=[{'label': c, 'value': c.lower()} for c in ['Red', 'Green', 'Blue']],
        value='red'
    ),
    html.Div(id='output-color'),
    dcc.RadioItems(
        id='dropdown-size',
        options=[{'label': i,
                  'value': j} for i, j in [('L','large'), ('M','medium'), ('S','small')]],
        value='medium'
    ),
    html.Div(id='output-size')

])

@app.callback(
    dash.dependencies.Output('output-color', 'children'),
    [dash.dependencies.Input('dropdown-color', 'value')])
def callback_color(dropdown_value):
    return "The selected color is %s." % dropdown_value

@app.callback(
    dash.dependencies.Output('output-size', 'children'),
    [dash.dependencies.Input('dropdown-color', 'value'),
     dash.dependencies.Input('dropdown-size', 'value')])
def callback_size(dropdown_color, dropdown_size):
    return "The chosen T-shirt is a %s %s one." %(dropdown_size,
                                                  dropdown_color)

Note that the DjangoDash constructor requires a name to be specified. This name is then used to identify the dash app in :ref:`templates <template_tags>`:

{%load plotly_dash%}

{%plotly_app name="SimpleExample"%}

Direct use in this manner, without any application state or use of live updating, is equivalent to inserting an iframe containing the URL of a Dash application.

Note

The registration code needs to be in a location that will be imported into the Django process before any model or template tag attempts to use it. The example Django application in the demo subdirectory achieves this through an import in the main urls.py file, but any views.py would also be sufficient.