I should be more specific: I cannot because the query depends on the
object instance:
class MyModel(models.Models):
fkey = models.ForeignKey(..., null=False)
count =
models.PosotiveIntegerField(default=lambda:MyModel.objects.filter(fkey_id= _?_
).count())
where _?_ should be the models's instance fkey attribute.
On 17:05 Wed 21 Aug , Simon Charette wrote:
> You can achieve this by setting a callable default value [1] on you field:
>
> class MyModel(models.Model):
> count =
> models.PositiveIntegerField(default=lambda:MyModel.objects.count())
>
> [1]
> https://docs.djangoproject.com/en/dev/ref/models/fields/#django.db.models.Field.default
> Le mercredi 21 août 2013 18:49:48 UTC-4, Marcin Szamotulski a écrit :
> >
> > Dear Django users,
> >
> > I am would like to set a default value on a model's field as a result of
> > a simple query. Something that in SQLAlchemy is done like that:
> > http://docs.sqlalchemy.org/en/rel_0_7/core/schema.html#sql-expressions
> >
> > Specifically I want to count some objects in the database and set this
> > count as the default value. I know that this can be done in two steps
> > first find the value then set it, but I would like to have it done
> > automatically.
> >
> > Best regards,
> > Marcin
> >
>
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