#27169: adding a field to a model with default value in postgres, when is
migrated
drop the default
-------------------------------+-----------------------------
Reporter: rockdolfolk | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 1.10
Severity: Normal | Keywords: tutorial, model
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------+-----------------------------
When I was studying the tutorial, I forgot the field "vote" in the model
Choise, so I defined later and done a new migration:
''(the development is in spanish)''
{{{
class Eleccion(models.Model):
pregunta = models.ForeignKey(Pregunta, on_delete=models.CASCADE)
eleccion_text = models.CharField(max_length=200)
votos = models.IntegerField(default=0) <=== new field
}}}
These are the log of the migration:
{{{
python manage.py makemigrations encuestas
Migrations for 'encuestas':
encuestas\migrations\0002_eleccion_votos.py:
- Add field votos to eleccion
python manage.py sqlmigrate encuestas 0002
BEGIN;
--
-- Add field votos to eleccion
--
ALTER TABLE "encuestas_eleccion" ADD COLUMN "votos" integer DEFAULT 0 NOT
NULL;
ALTER TABLE "encuestas_eleccion" ALTER COLUMN "votos" DROP DEFAULT;
<=== ???
COMMIT;
python manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, encuestas, sessions
Running migrations:
Rendering model states... DONE
Applying encuestas.0002_eleccion_votos... OK
}}}
This is the final table:
{{{
CREATE TABLE encuestas.encuestas_eleccion
(
id serial NOT NULL,
eleccion_text character varying(200) NOT NULL,
pregunta_id integer NOT NULL,
votos integer NOT NULL, <=== it has not default value
CONSTRAINT encuestas_eleccion_pkey PRIMARY KEY (id),
CONSTRAINT
encuestas_eleccio_pregunta_id_9558286d_fk_encuestas_pregunta_id FOREIGN
KEY (pregunta_id)
REFERENCES encuestas.encuestas_pregunta (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION DEFERRABLE INITIALLY
DEFERRED
)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/27169>
Django <https://code.djangoproject.com/>
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