Disclaimers:
1. This issue is also on StackOverflow:
https://stackoverflow.com/questions/64320386/django-postgresql-model-with-only-foreign-keys
2. I posted this here in this group a couple of days ago without finding
a solution.
I must admit I am quite baffled by this problem, seems like a thing I have
done for years suddenly does not work any longer?? In particular the code
in question here has worked for a couple of months, and then "suddenly"
stopped working - probably due to "apt get upgrade", but I can not pinpoint
exactly when it stopped working. I post it again here with some corrections
and a bit more detail. Hopefully someone can see what I do wrong; if
someone wants to contact me off-list and offer commercial help I could be
interested in that.
I have a model which looks like this:
class InputTypeMap(models.Model):
input_type = models.ForeignKey(InputType, on_delete=models.CASCADE)
training = models.ForeignKey(Training, on_delete=models.CASCADE)
category = models.ForeignKey(Category, on_delete=models.CASCADE)
gender = models.ForeignKey(Gender, on_delete=models.CASCADE)
I.e. there are four fields in the model which are all foreign keys to other
models. The primary key is not added explicitly by me, rather I trust
Django to add the required primary key with an "invisible" AutoField. When
I create a new instance of this class like:
InputTypeMap.objects.create(input_type=input_type,
training=training,
gender=gender,
category=category)
I get an exception:
Traceback (most recent call last):
File
"/home/hove/sleipner/venv/lib/python3.7/site-packages/django/db/backends/utils.py",
line 84, in _execute
return self.cursor.execute(sql, params)
psycopg2.errors.NotNullViolation: null value in column "id" violates
not-null constraint
DETAIL: Failing row contains (null, Maintenance, Female, MareGielding, No).
>From the error message it seems to me that a ID key for the new entry is
not generated; I was expecting postgres to do that itself? When the same
code is run as a test on sqlite it works as intended.
Information about Postgres versions: Server 9.6 - Client 13
Joakim
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