django get_or_create throws Integrity Error - django

Question

I have read this thread:
get_or_create throws Integrity Error
But still not fully understand when get_or_create returns False or IntegrityError.
I have the following code:
django_username = 'me'
user = get_user_model().objects.filter(username=django_username).first()
action_history, action_added = ActionModel.objects.get_or_create(
date=date_obj, # date object
account_name=unique_name, # e.g. account1234
target=follower_obj, # another model in django
user=user, # connected django user
defaults={'identifier': history['user_id']}
)
While the model looks like:
class ActionModel(models.Model):
"""
A model to store action history.
"""
identifier = models.BigIntegerField(
_("identifier"), null=True, blank=True) # target id
account_name = models.CharField(_("AccountName"), max_length=150, null=True, blank=True) # account name of the client
date = models.DateField(_("Date"), auto_now=False, auto_now_add=False) # action date
target = models.ForeignKey(Follower, verbose_name=_("Target"), on_delete=models.CASCADE) # username of the done-on action
user = models.ForeignKey(
settings.AUTH_USER_MODEL,
on_delete=models.CASCADE,
null=True,
editable=False,
db_index=True,
) # django user that performed the action
class Meta:
verbose_name = _("Action")
verbose_name_plural = _("Actions")
unique_together = [
['account_name','date','target'],
]
Sometimes it return IntegrityError, and sometimes (when unique constrain exists it will return False on created).

Answer 1

You have unique_together constraint.
Lets imagine you have object in db with following data
account_name='bob', date='2020-12-12', target='b', user='12'
In you get_or_create method you are doing this
ActionModel.objects.get_or_create(
date='2020-12-12',
account_name='bob',
target='b',
user="13"
)
you providing exactly this three parameters with this data, but user this time is 13, so django could not find any object and it tries to create one, but with this parametres you cant create object because there is unique constraint

Answer 2

OK.
I figured it out, I sent:
account_name = 'adi'
date = '07-02-21'
target = 'nana1'
user = 'me'
While it was not exist with the specific user = 'me' but with user = None:
account_name = 'adi'
date = '07-02-21'
target = 'nana1'
user = None
So the get was failing and the created try to duplicate the unique_together = ['account_name','date','target'].