Optional foreign key with django?

[maroxe]

Hi, In my models I want to have an optional field to a foreign key. I
tried this:

field = models.ForeignKey(MyModel, null=True, blank=True,
default=None)

But i am getting this error:

model.mymodel_id may not be NULL

i am using sqlite edit: if it can help, here is the exception
location:

/usr/lib/python2.6/site-packages/django/db/backends/sqlite3/base.py
in execute, line 200

so it's sqlite specific problem, i think.

PS: i droped the whole table and synced before getting this error.

[akaariai]

This should just work (TM). Are you sure the table is dropped and
recreated correctly? The error is from the database (not from Django
code), and the reason is a not null constraint on models.mymodel_id
which should not exist. Maybe you could try this in completely clean
database?

- Anssi

[bagheera]

I have same problem with sqlite. Try another database. Django devs suggest
postgres.
--
Linux user

[Carlton Gibson]

On 9 Sep 2010, at 12:04, bagheera wrote:

>> On Sep 8, 11:14 pm, maroxe <bachir...@gmail.com> wrote:
>>> Hi, In my models I want to have an optional field to a foreign key. I
>>> tried this:
>>>
>>> field = models.ForeignKey(MyModel, null=True, blank=True,
>>> default=None)
>>>
>>> But i am getting this error:
>>>
>>> model.mymodel_id may not be NULL

I think the error is that SQLite treats columns with defaults as NOT NULL.

As far as I can see, you don't need the `default=None` in your model declaration. Change it to:

field = models.ForeignKey(MyModel, null=True, blank=True)

-- I have multiple apps using SQLite that do exactly this, so to quote an earlier post, "this should just work (TM)"

HTH

Regards,
Carlton

[maroxe]

This solved my problem