Callbacks stop working in multipage app if there's multiple Outputs

@antony66 wrote:

Hi everyone!

I’ve recently discovered that if I create a multipage app according to https://dash.plotly.com/urls and some of my apps pages contain a callback with multiple outputs, it doesn’t work.

Here is my example code:

app.py:

import dash

app = dash.Dash(__name__)
server = app.server
app.config.suppress_callback_exceptions = True

index.py:

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

from app import app
from apps import master, detail


app.layout = html.Div([
    dcc.Location(id='url', refresh=False),
    html.Div(id='page-content')
])


@app.callback(Output('page-content', 'children'),
              [Input('url', 'pathname')])
def display_page(pathname):
    if pathname == '/':
        return master.layout
    elif pathname == '/detail':
        return detail.layout
    else:
        return '404'

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

master.py:

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

from app import app

items = [f'item{i}' for i in range(1,10)]

layout = html.Div([
    html.H3('Master'),
    html.Div([
        dcc.Link(children=item, href=f'/detail?id={item}') for item in items
    ], id='master-items'),
])

detail.py that works:

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

from app import app

layout = html.Div([
        html.H3(id='detail-title'),
        html.H3(id='detail-title2'),
])

@app.callback(Output('detail-title', 'children'),
              [Input('url', 'search')])
def update_detail_title(query):
    return 'aaaa ' + query

detail.py that doesn’t work:

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

from app import app

layout = html.Div([
        html.H3(id='detail-title'),
        html.H3(id='detail-title2'),
])

@app.callback([Output('detail-title', 'children'), Output('detail-title2', 'children')],
              [Input('url', 'search')])
def update_detail_title(query):
    return 'aaaa ' + query, 'bbb'

Isn’t it a bug?

Posts: 3

Participants: 2

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