Field filters on dynamic columns


I have a dataset where some date fields are represented as strings (this is another problem, but one I hope shouldn’t affect metabase). This means that in my queries I sometimes cast these columns to something that I can operate on, e.g.

SELECT created_at::timestamp FROM my_table

The problem is, if I want a dashboard filter on this column, it only allows me to reference the database columns and not the column in my results table. Therefore it doesn’t detect it as a field type that can be properly filtered.

Is there a way around this?