[BUG] dcc.Location callback fires twice IDENTICALLY

As far as I can tell, this flavor of the "duplicate dcc.Location callback" issue (#883) hasn't been documented yet. When I run a multipage app, reloading the page fires the callback twice with the same href / pathname / search payload. This is distinct from the other issue of having the callback return None and then returning the proper value(s).

import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
import dash_bootstrap_components as dbc
import dash
import urllib

navbar = dbc.NavbarSimple(
    brand='Frac Planning App',
    brand_href='/',
    sticky='top',
)

body = dbc.Container(
    dbc.Row(
        dbc.Col(id='page-content')
    )
)

app.layout = html.Div([
    dcc.Location(id='url', refresh=False),
    navbar,
    body
])

@app.callback(Output('page-content', 'children'),
              [Input('url', 'href')],
              [State('url', 'pathname'), State('url', 'search')])
def display_page(href, pathname, search):
    print('HREF:', href)
    print('PATHAME:', pathname)
    print('SEARCH:', search)
    url = urllib.parse.urlparse(href)
    # print('RAW pathname:', url)
    print('TRIGGER(S):', [i['prop_id'] for i in dash.callback_context.triggered])
    if url.path == '/':
        return form.layout
    elif url.path == '/result':
        query = dict(urllib.parse.parse_qsl(url.query))
        return result.plot(**query)
    else:
        raise dash.exceptions.PreventUpdate

Here is the output. It doesn't always print in the same order:

HREF: http://houmedge201:5004/
PATHAME: /
HREF: http://houmedge201:5004/
SEARCH: 
PATHAME: /
TRIGGER(S): ['url.href']
SEARCH: 
TRIGGER(S): ['url.href']

Running on Linux. Versions used:

dash                       1.7.0
dash-core-components       1.6.0
dash-html-components       1.0.2
dash-renderer              1.2.2

I've tried the fix mentioned in #883 (comment) to no avail. Solving this is mission critical for my app because the duplicate callback crashes a subsequent database query.

Changing href via a html.Link makes the callback fire only once. However, users need to be able to share app URLs with query params, which right now is broken due to this bug.

Is anyone else experiencing this issue?

🙋‍♂️

Me as well

Same

me too!

me too. I tried to avoid the second time execution by using a data_store flag but for some reason, as the states and inputs are exactly the same, this can't be accomplished

I am experiencing the same issue. Callback with a 'pathname' property as input is being triggered 4 times. The result is that a chart on another page takes a few seconds to appear rather than appear instantly when I click on the button for that page. Critical issue.

plotly#1049: dcc.Location callback fires twice, do not triggerDefault…

I'm experiencing this issue too.
Digging a bit in the source code, it seems a dash-renderer problem with some components default state.
Here is a quick fix to avoid this problem in Location component (jgoday@5681290).

Need to figure out why this is happening with the location component anyway, maybe the real problem resides in dash-core-components/src/components/Loading.react.js ...) 🤔

Is anyone else experiencing this issue?

Me too.

I'm having the same issue on dash 1.9.1.

Having the same issue here unfortunately

Having the same problem, no fix for this?

Is there any fix? Or a workaround for this available?

I'm still having this issue with dash 2.3.1, did anybody find working solution?

@alexcjohnson

@alexcjohnson @T4rk1n sorry for the personal tag, but thought it might be useful to make sure that this issue has some more visibility and is on the roadmap.

I assume its been buried in the backlog in the last two years, but seems like its still an issue for many users.

Still present in dash 2.6.1 :(

Thankfully there's streamlit instead now to develop in. How can it be three years, a javascript fix posted, and direct dev tags, but not even a comment from any of the core team?

@Samreay

Hey @Samreay, @luggie, or @Stayermax, do you have a minimal reproducible example of a Dash app that exhibits the Location callback firing twice?

Looking back through the history of the issue, I can't actually find any code that can be used to reproduce the issue, which makes triage/diagnosis of the problem difficult. There are likely other possible causes of duplicate callbacks firing based on custom code/env setup, which would need to be eliminated from possibility.

I had a a go at creating a minimal reproducible example from the original post (which itself was not reproducible), but don't see the behaviour. Do you in your setup? or does the example need to be changed?

from dash import Dash, html, dcc, Input, State, Output

app = Dash(__name__)

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


@app.callback(
    Output("page-content", "children"),
    Input("url", "href"),
    State("url", "pathname"),
    State("url", "search"),
)
def display_page(href, pathname, search):
    print("HREF:", href)
    print("PATHAME:", pathname)
    print("SEARCH:", search)
    if pathname == "/":
        return html.Div(f"HOME - Search: {search}")
    return html.Div(f"{pathname} - Search: {search}")


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

Apologies mate, I'm now in a different role at a different company, so don't have access to the source to try and create a minimal example.

@Samreay

Hey @Samreay, @luggie, or @Stayermax, do you have a minimal reproducible example of a Dash app that exhibits the Location callback firing twice?

Looking back through the history of the issue, I can't actually find any code that can be used to reproduce the issue, which makes triage/diagnosis of the problem difficult. There are likely other possible causes of duplicate callbacks firing based on custom code/env setup, which would need to be eliminated from possibility.

I had a a go at creating a minimal reproducible example from the original post (which itself was not reproducible), but don't see the behaviour. Do you in your setup? or does the example need to be changed?
from dash import Dash, html, dcc, Input, State, Output

app = Dash(__name__)

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


@app.callback(
    Output("page-content", "children"),
    Input("url", "href"),
    State("url", "pathname"),
    State("url", "search"),
)
def display_page(href, pathname, search):
    print("HREF:", href)
    print("PATHAME:", pathname)
    print("SEARCH:", search)
    if pathname == "/":
        return html.Div(f"HOME - Search: {search}")
    return html.Div(f"{pathname} - Search: {search}")


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

It's been a while since I worked on dash, but I created a minimal repro, but unfortunately only in the older versions:

dash==1.9.0
dash-renderer==1.7.0
Flask==2.0.0
Jinja2==3.0.3
markupsafe==2.1.1
werkzeug==2.0.0
itsdangerous==0.24

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

app = dash.Dash()

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

@app.callback(Output('content', 'children'),
              [Input('url', 'pathname')])
def display_page(pathname):
    print(f'you are now at: {pathname}')
    return pathname

app.run_server(host='0.0.0.0', debug=True)

Sorry, I also don’t have the code. From: serensoner ***@***.***> Date: Sunday, 23 October 2022 at 15:37 To: plotly/dash ***@***.***> Cc: Pankratov Vitaly ***@***.***>, Mention ***@***.***> Subject: Re: [plotly/dash] [BUG] dcc.Location callback fires twice IDENTICALLY (#1049) Hey @Samreay<https://github.com/Samreay>, @luggie<https://github.com/luggie>, or @Stayermax<https://github.com/Stayermax>, do you have a minimal reproducible example of a Dash app that exhibits the Location callback firing twice? Looking back through the history of the issue, I can't actually find any code that can be used to reproduce the issue, which makes triage/diagnosis of the problem difficult. There are likely other possible causes of duplicate callbacks firing based on custom code/env setup, which would need to be eliminated from possibility. I had a a go at creating a minimal reproducible example from the original post (which itself was not reproducible), but don't see the behaviour. Do you in your setup? or does the example need to be changed? from dash import Dash, html, dcc, Input, State, Output app = Dash(__name__) app.layout = html.Div([html.Div(id="page-content"), dcc.Location(id="url")]) @app.callback( Output("page-content", "children"), Input("url", "href"), State("url", "pathname"), State("url", "search"), ) def display_page(href, pathname, search): print("HREF:", href) print("PATHAME:", pathname) print("SEARCH:", search) if pathname == "/": return html.Div(f"HOME - Search: {search}") return html.Div(f"{pathname} - Search: {search}") if __name__ == "__main__": app.run_server(debug=True) It's been a while since I worked on dash, but I created a minimal repro, but unfortunately only in the older versions: requirements.txt dash==1.9.0 dash-renderer==1.7.0 Flask==2.0.0 Jinja2==3.0.3 markupsafe==2.1.1 werkzeug==2.0.0 itsdangerous==0.24 `main.py `import dash_core_components as dcc import dash_html_components as html from dash.dependencies import Input, Output import dash app = dash.Dash() app.layout = html.Div([ dcc.Location(id='url', refresh=False), html.Div(id='content'), ]) @app.callback(Output('content', 'children'), [Input('url', 'pathname')]) def display_page(pathname): print(f'you are now at: {pathname}') return pathname app.run_server(host='0.0.0.0', debug=True) ` — Reply to this email directly, view it on GitHub<#1049 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AJFOCUG3AZ4CUNEQAXUNXBDWEUWQ7ANCNFSM4J3PPKIQ>. You are receiving this because you were mentioned.Message ID: ***@***.***>

@serensoner

Thanks heaps @serensoner! I can confirm that your example has duplicate callback invocations, when run with Dash 1.9. However not on the most recent Dash, where there's only one callback invocation. Bisecting suggests that this bug was actually fixed in Dash 1.16.... which was released September 4 2020, interestingly, about the time you were speculating @alexcjohnson that this bug could have been fixed: plotly/dash-core-components#858 (comment)

@alexcjohnson, given we can't identify a reproducible example showing this bug in the latest Dash, maybe this issue should be closed? If someone is able to come up with an example showing it's still there, might be better to start with a fresh issue.

@ned2

@ned2 thanks for digging into this. Good to know at least some of these cases have been fixed! @luggie any chance you can post an app showing the problem you're still seeing? We really need a reproduction case in order to get to the bottom of this. After plotly/dash-core-components#858 (comment) I seem to have felt we had more to do:

The boundaries of the problem have changed a little, as evidenced by this test, but it’s definitely not fixed.

but my comment may just have been based on the preceding comment by @astrowonk rather than having seen the problem myself.

@ned2

@ned2 thanks for digging into this. Good to know at least some of these cases have been fixed! @luggie any chance you can post an app showing the problem you're still seeing? We really need a reproduction case in order to get to the bottom of this. After plotly/dash-core-components#858 (comment) I seem to have felt we had more to do:

The boundaries of the problem have changed a little, as evidenced by this test, but it’s definitely not fixed.

but my comment may just have been based on the preceding comment by @astrowonk rather than having seen the problem myself.

It's worth noting that whatever I was experiencing was unrelated to this issue. My old comment on the other issue/PR was inaccurate. I am not aware of this issue affecting anything I'm doing at the moment.

@gvwilson

Hi - we are tidying up stale issues and PRs in Plotly's public repositories so that we can focus on things that are most important to our community. If this issue is still a concern, please add a comment letting us know what recent version of our software you've checked it with so that I can reopen it and add it to our backlog. (Please note that we will give priority to reports that include a short reproducible example.) If you'd like to submit a PR, we'd be happy to prioritize a review, and if it's a request for tech support, please post in our community forum. Thank you - @gvwilson

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[BUG] dcc.Location callback fires twice IDENTICALLY #1049

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[BUG] dcc.Location callback fires twice IDENTICALLY #1049

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ned2 commented on Oct 20, 2022

Samreay commented on Oct 21, 2022

serensoner commented on Oct 23, 2022

Stayermax commented on Oct 23, 2022

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astrowonk commented on Nov 4, 2022

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