How do you specify a default for the Django ForeignKey field?

Question

I’m trying to add a ForeignKey field to a Django model using South. I’m getting the following error:

ValueError: You cannot add a null=False column without a default value.

I did, in fact, specify a default value for the field, but I’m not sure I did it correctly.

language = models.ForeignKey(Language, default=Language.objects.all()[0])

Should this work?

Answer 1

AFAIK Django won't execute a QuerySet passed as a param, even if it's limited to one element. You should try something like proposed in this post

class Foo(models.Model):
    a = models.CharField(max_length=10)

def get_foo():
    return Foo.objects.get_or_create(id=1)

class Bar(models.Model):
    b = models.CharField(max_length=10)
    a = models.ForeignKey(Foo, default=get_foo)

Answer 2

Because get_or_create returns a tuple, I think this is a better solution

def get_default():
    result, _ = Foo.objects.get_or_create(id=1)
    return result

than this

return Foo.objects.get_or_create(id=1)