Django: Get next primary key for object.

get_next_primary_key.py

from djangobb_forum.models import Post
from django.db.models import Max

# id__max is None if there are no Posts in the database
id_max = Post.objects.all().aggregate(Max('id'))['id__max']
id_next = id_max + 1 if id_max else 1

The problem with this is that if several functions call this, they will get the same ID. The best solution will involve invoking the database's next sequence function so that the ID that is returned is only returned once.

So far I've really only seen database specific solutions. The following works for PostgreSQL.

def get_next_id(model_class):
        from django.db import connection
        cursor = connection.cursor()
        cursor.execute( "select nextval('%s_id_seq')" % \
                        model_class._meta.db_table)
        row = cursor.fetchone()
        cursor.close()
        return row[0]

This following snippet works for MySQL.
https://djangosnippets.org/snippets/1415/