[BUG] search_value triggers unrelated callbacks, making dropdown search unusable

[oegedijk]

While chasing down a bug in explainerdashboard, I noticed that when you have a dynamic server side dropdown search, and also have a callback targeting dropdown.value, then this latter gets triggered everytime you search in the dropdown. Usually with unwanted side effects. In this case it makes the dropdown search completely unusable.

Below an example, with a dropdown, and a select random item button. Searching in the dropdown triggers the button callback. Including a callback.context check to see if the button callback was indeed triggered by the button n_clicks input seems to fix the problem.

import random
import dash
from dash import Dash, dcc, html, dcc, Input, Output, State
from dash.exceptions import PreventUpdate

options = [str(i) for i in range(1000)]

app = Dash(__name__)
app.layout = html.Div([
    html.Div(id='dropdown-output'),
    html.Button("Random Button", id='button'),
    dcc.Checklist(options=['fix bug'], value=[], id='fix-bug'),
    dcc.Dropdown(id="index-dropdown", value="654")   
])
    
@app.callback(
    Output("index-dropdown", "value"),
    Input("button", "n_clicks"),
    State('fix-bug', 'value'),
)
def random_index(n_clicks, fix_bug):
    print("triggered random click!")
    if fix_bug and dash.callback_context.triggered_id != 'button':
       raise PreventUpdate
    return random.choice(options)

@app.callback(
    Output("index-dropdown", "options"),
    Input("index-dropdown", "search_value")
)
def update_options(search_value):
    if not search_value:
        raise PreventUpdate
    return [o for o in options if str(search_value) in o]

@app.callback(
    Output("dropdown-output", "children"),
    Input("index-dropdown", "value")
)
def send_output(index):
    return f"selected {index}!"

app.run_server(port=8051, debug=False)

[T4rk1n]

Duplicate of #2411

[T4rk1n]

Fixed along with #2411

[sergiykhan]

I have just used an example provided by @oegedijk in Dash 2.9.2 and the problem is still there.

[bambinobino]

Same thing here, having the problem still in 2.9.2

[oegedijk]

@T4rk1n could we add a failing test for this so that it will get fixed in the next release?

[bambinobino]

@T4rk1n could we add a failing test for this so that it will get fixed in the next release?

I believe this is fixed in Dash v2.10.2

[sergiykhan]

Indeed, fixed in 2.10.1
https://github.com/plotly/dash/releases