Django: Change TimeField to DateTimeField in models.py
django, postgresql, python, sql
Solution
That's because `time` cannot be converted (casted) to `timestamp` (neither their time-zone related variants) in PostgreSQL. F.ex. this will also fail:
SELECT 'now'::time::timestamp
In these cases, you should use the `USING` clause in your `ALTER TABLE` statement (if you can edit it directly):
ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
ALTER [ COLUMN ] column_name
[ SET DATA ] TYPE data_type [ COLLATE collation ] [ USING expression ]
Your query will look like, f.ex.:
ALTER TABLE "my_model"
ALTER COLUMN "column_name"
SET DATA TYPE TIMESTAMP WITH TIME ZONE USING 'yesterday'::date + "column_name"
Problem
In my models.py, i have some models with this kind of attributes: ``` timestamp = models.TimeField(default=0) ``` I want to change them to: ``` timestamp = models.DateTimeField(default=0) ``` Using ``` python manage.py schemamigration app --auto ``` works in first instance. But ``` python manage.py migrate app ``` leads to this error: ``` django.db.utils.ProgrammingError: column "timestamp" cannot be cast to type timestamp with time zone ``` So i somehow needs to make this casting possible. For every time without date i want to set a default date (e.g. yesterday). How can i do this? I only found this on SO, which does not help at all because of that error. BTW: I am using postgres and python3. I appreciate your help! It is okay for me to use SQL direct on the database (without south) if that's easier