Dependent Dropdowns

[bpolasek]

Hi! Does anyone know how to make one dropdown element depend on another? I have a list of 130 engines that are categorized by 4 regions. I want the first dropdown to be the region and the second dropdown to fill the specific engines for that region.

I’m new to Dash but have been working with Flask. I got it to work in Flask but using JavaScript. Not sure if that translates into Dash well.

Let me know if that makes sense and if you have any ideas! Thanks!

[adamschroeder]

hi @bpolasek

Welcome to the community.

That is what we call a chained callback.

You can find a few more examples in the Dash Example Index, under the callbacks → chained section

[bpolasek]

Okay thanks! I will have to check it out!

[AIMPED]

Hi @bpolasek, in addition to @adamschroeder’s example here is another one:

The dropdown value auto change base on first filter

Hi @Eddy , Basically you want the options of a dcc.Dropdown to be populated based on the selection of an other dcc.Dropdown. Since you are using pandas anyways, you could do something like this: from dash import Dash, Input, Output, html, dcc import dash_bootstrap_components as dbc import pandas as pd df = pd.DataFrame( { 'process': ['A', 'A', 'B', 'B', 'C', 'C'], 'code': [f'CODE{i}' for i in range(1, 7)], 'data': [1 for _ in range(6)] } ) app = Dash(__name__,…

[bpolasek]

Thank you!!