Django and PostgreSQL sequence for primary key autoincrement

Question

I have the following table and sequence in my postgresql-8.4 database:

CREATE TABLE complexobjectpy
(
  id integer NOT NULL,
  the_geom geometry,
  semcat integer,
  CONSTRAINT complexobjectpy_pkey PRIMARY KEY (id),
  CONSTRAINT enforce_dims_the_geom CHECK (st_ndims(the_geom) = 2),
  CONSTRAINT enforce_srid_the_geom CHECK (st_srid(the_geom) = 900913)
)
WITH (
  OIDS=FALSE
);
ALTER TABLE complexobjectpy OWNER TO tss;

CREATE SEQUENCE seq_complexobjectpy
  INCREMENT 1
  MINVALUE 1
  MAXVALUE 9223372036854775807
  START 1
  CACHE 1;
ALTER TABLE seq_complexobjectpy OWNER TO tss;

The following is instead my Django model:

class Complexobjectpy(models.Model):
    the_geom = models.GeometryField(srid=900913)
    semcat = models.IntegerField()
    objects = models.GeoManager()
    class Meta:
        db_table = u'complexobjectpy'

Performing the following query:

myObj = Complexobjectpy(semcat=50, the_geom=geometryMerged.wkt)
myObj.save(using='u1')

I get the error:

IntegrityError: null value in column "id" violates not-null constraint

Why I get this? Reading the documentation I was expecting that the id value would be chosen automatically using the sequence...

Answer 1

Actually I am providing this as an answer. The datatype serial in postgres is an auto incremental four-byte integer. If you change your id from integer to serial this would work.

 id serial NOT NULL

Read more: http://www.postgresql.org/docs/8.4/static/datatype.html