How to get the index of a trigger component

Dash Python
2

Hi @Eduardo

That’s a good question and I think it would be nice to have an example added to the docs :slight_smile:

Since dash.callback_context.triggered returns a string, there are lots of different ways to get the number. We could start a debate on which of these methods is the most Pythonic: regex - How to extract numbers from a string in Python? - Stack Overflow

Here is my favorite way :

Given that the prop_id is a stringified dictionary with no white space – which is a JSON format, you can use the json module to convert it back into a normal python dictionary. See the json.loads() method - more info on that here: Python JSON

I use this method to get the chart number to delete in this example: Pattern call-backs regarding adding dynamic graphs - #4 by AnnMarieW

import json
...

input_id = dash.callback_context.triggered[0]["prop_id"].split(".")[0]
index_number = json.loads(input_id)["index"]

Does anyone else have a better solution?

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