For my django app, I want to convert datetimefield to datefield. That resulting in an error :
Date truncation for column ...
Can you please tell me how to do this ?
I have tried this:
I have written a datamigration before schemamigration that modifies values of datetimefield from datetime to date .
obj.datetimefield = obj.datetimefield.date()
obj.save() --- error here.
How do you expect that to work without a schemamigration?
You could add an extra field to your model, then run your code to copy it from the old field to the new field after some modification(s). Then you can delete the old field and finally rename the new field.
But honestly, you should have a look at South, an excellent and common used tool for migrating django models.