JSONField in PostgreSQL varchar limit 256

Using Django
#1

Hi All,

I’ve been searching for solution for a while now and can’t find a way to change the default length of the JSONField in PostgreSQL. I know it’s stored as VarChar (checked it in the database) and the length is 256. I guess this is some default value somewhere (PostgreSQL or Django CharField?).
I did a workaround now and just defined my field as CharField with set_ and get_ also defined in the model, but it’s not elegant.

Do I miss something in JSONField?

Thanks folks!
Gabor

#2

That must be an artifact of an older database or migration. The current versions of PostgreSQL stores a JSONField as a JSONB field type.

#3

I have started with a new database, PostgreSQL 13, and erased all the migration files in Django before makemigration and migrate.
But maybe I did an initial migration before, with the CharField solution and then the field type has not changed in PostgreSQL after new migration requests (even with no migration files in Django)

I will try and delete all the tables again and see what happens.

#4

When I start from an empty database Django creates JSONB field type indeed. Unfortunately the migration doesn’t change it. Can we report it somewhere?

#5

What do you mean by “the migration doesn’t change it”? A lot depends upon what was done from the very beginning and how migrations were handled along the way. Are you saying that this was originally a VarChar field and then changed to a JSON Field?

If you don’t have a continuous and uninterrupted chain of migration files from initial table creation to present, I don’t think there’s anything to report. (On the other hand, if you’ve got such a chain that shows that field was originally a CharField, then subsequently changed to a JSONField and no ALTER TABLE was generated, that might be worth reporting.)