Existing histogram slices are broken

[michellethomas]

Testing what's on master, I noticed that all of our existing histogram slices are broken with the error message Must have at least one numeric column specified. This error shows up when there's no data in all_columns_x (Numeric Columns). In the params they all have all_columns_x set as a string. It looks like in the PR here this was changed to a multi field where the value would be a list.

@mistercrunch would changing a SelectControl to multi: true break existing slices? Do we need a db migration for this or is there some other way we can catch this?

• I have checked the superset logs for python stacktraces and included it here as text if any
• I have reproduced the issue with at least the latest released version of superset
• I have checked the issue tracker for the same issue and I haven't found one similar

Expected results

Existing histograms load correctly

Actual results

Existing histograms load with the error

Steps to reproduce

Load a histogram created before this PR was introduced.

@mistercrunch @ArielStv

[michellethomas]

@mistercrunch thoughts on this? do we need a db migration to handle this case where a single value select was changed to multi: true?

[mistercrunch]

I should have caught this in code review. So either we do a db migration or do some magic around SelectControl that would wrap value if it's not an array and multi: true