Django Oracle integrity error when saving any instance to database - sql

Question

I'm doing a migration from sqlite to oracle backend. The oracle database already exists and is maintained by other people. Its version is Oracle9i Enterprise Edition Release 9.2.0.1.0.
I have a simple model:
class AliasType(models.Model):
id = models.AutoField(primary_key=True, db_column="F_ALIAS_ID")
name = models.CharField(u"Type name", max_length=255, unique=True, db_column="F_ALIAS_NAME")
class Meta:
db_table = "ALIAS"
./manage.py syncdb does not return any errors. But when I try to create a new instance and save it to the database, I get the following error:
>>> AliasType.objects.create(name="test")
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/manager.py", line 138, in create
return self.get_query_set().create(**kwargs)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/query.py", line 360, in create
obj.save(force_insert=True, using=self.db)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/base.py", line 460, in save
self.save_base(using=using, force_insert=force_insert, force_update=force_update)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/base.py", line 553, in save_base
result = manager._insert(values, return_id=update_pk, using=using)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/manager.py", line 195, in _insert
return insert_query(self.model, values, **kwargs)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/query.py", line 1435, in insert_query
return query.get_compiler(using=using).execute_sql(return_id)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/sql/compiler.py", line 791, in execute_sql
cursor = super(SQLInsertCompiler, self).execute_sql(None)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/models/sql/compiler.py", line 735, in execute_sql
cursor.execute(sql, params)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/backends/util.py", line 18, in execute
return self.cursor.execute(sql, params)
File "/mnt/Data/private/projects/envs/termary-oracle/src/django/django/db/backends/oracle/base.py", line 630, in execute
return self.cursor.execute(query, self._param_generator(params))
IntegrityError: ORA-01400: cannot insert NULL into ("SINCE"."ALIAS"."F_ALIAS_ID")
If I specify id, e.g. AliasType.objects.create(id=5, name="test"), it works. I thought django should be able to retrieve id value automatically. I've learnt that Oracle does not support autoincrement, and I should use triggers and sequences. I was told that there is an existing sequence in the database that returns ids for all new rows, and I know its name, say SEQ_GET_NEW_ID.
So the question is how to implement that in the most elegant way, i.e. how to tell Django to get id values for all new objects from the sequence named SEQ_GET_NEW_ID without hacking it too much (e.g. overriding save() methods for all models)?

Answer 1

There is a ticket open (#1946) to allow exactly that, overriding the default sequence name. But as it's not closed yet, I don't think there is a way without hacking.
I haven't used Oracle before, but a quick search suggests that it is possible to create aliases/synonyms for sequences. manage.py sqlall <app> should show you the sequence name Django is expecting. So you probably could just make this an alias for SEQ_GET_NEW_ID.