I’m developing an app which chains together several elements to dynamically filter through songs from a collection of music. The general flow looks like this. Spotify URI elements are parsed from the page URL, and the playlist/library is retrieved via the Spotify API, then stored in a hidden div. …

In a lot of callback functions I just add something like: from dash.exceptions import PreventUpdate ... @app.callback(...) def this_function(var, ... ): if var==None: raise PreventUpdate # other code It’s not perfect, but it works for my stuff. Is this helpful? If not, some more…

Thank you both! These are exactly the solutions I was hoping for. I ended up returning no_update values. This felt better to me than raising exceptions because everything is working as intended.

Errors from None inputs with chained callbacks

Dash Python

flyingcujo May 16, 2019, 2:42pm 3

Check this out. 📣 Dash 0.41.0 released Specifically the section on Partial Multi-Output - the noupdate feature might work better than passing back None depending on your app implementation.

Topic		Replies	Views
Callback triggers but returns nothing Dash Python	1	578	September 24, 2021
Error - Expected the output type to be a list or tuple but got None Dash Python	7	10151	June 20, 2020
Dash Core Components callback error Dash Python	5	10249	February 19, 2019
Declaring callbacks with some non-existing Inputs results in a JS error Dash Python	5	2144	January 21, 2019
Dash Exception : Received value of type <class 'NoneType'> Dash Python	1	3371	December 9, 2021

Errors from None inputs with chained callbacks

Related topics