Value too long for type character varying(24)

[dikshajiwane]

My test cases getting fail since I switch the test database backend from SQLite to Postgres. I am creating a model instance using mixer and it is throwing the following error.
"Value too long for type character varying(24)"
There is a field where it is showing the error:
code = models.CharField(_('Code'), max_length=24, null=False, blank=False,
db_column='code', default=uuid.uuid4, unique=True)
I am not getting whats wrong with it.
Please help.