Hi Dash Community,
I have a question I have been struggling with today regarding the behavior of residual dropdown values after options have been modified.
Consider 3 dropdowns used to generate a graph from some data:
Dropdown 1: Selection of years
[2015, 2016, 2017, 2018, 2019]
Dropdown 2: Selection of companies based on Dropdown 1:
[if 2015: Company A, B, C]
[if 2017: Company A, B, C, D, E]
Dropdown 3: Pull out a slice of a pie chart
[Slice 1, Slice 2, etc.]
If company E is selected, and the year is changed from 2017 to 2015, the graph disappears as intended,
the selection appears cleared, and Dropdown 2 options are updated.
However, if company E is selected while there is a value in Dropdown 3, and the year is changed to 2015,
the value that appeared cleared causes an error as there is no data for that criteria.
Is there a way to set the value of Dropdown 2 to something like none type in this scenario?
The condition could be that it is not found in the dropdown.
I cannot change the value of Dropdown 2 explicitly as it is one of my input values,
and you cannot have the same input and output.