What is the difference between Input and State?

Dash Python
1

I am a little bit confused with the difference of app.Callback Input and State. Let’s say there are two options for a range slider when the callback is fired:

    Input('my-range-slider', 'value'),
    State('my-range-slider', 'value')

What is the practical difference between each? When should one use over the other?

2 Likes
2

Inputs will trigger your callback; State do not. If you need the the current “value” - aka State - of other dash components within your callback, you pass them along via State.

See https://dash.plot.ly/state for some examples.

1 Like
3

What you said does make sense. So using state could reduce the number of callbacks which gives a better performance?

4

Not sure I follow that. Depending on how you construct your callbacks, and how much data you pass around, could affect performance. Your callbacks are triggered whenever the Input conditions are met; generally speaking, I don’t see how including (or not including) State parameters will provide better performance.