Django models: default value for column

Question

I have following Django model code:

status = models.PositiveIntegerField(default = 0b000)
comments_allowed = models.BooleanField(default = True) # whether comments are allowed to this post

But I expected, it would generate SQL like

`status` integer NOT NULL default '4',
`comments_allowed` bool NOT NULL default TRUE

Which is not happening and when I run manage.py sqlall appname it produces:

`status` integer UNSIGNED NOT NULL,
`comments_allowed` bool NOT NULL

Delving into Django's code and googling gave me nothing, but James Bennet's comment that default is not assumed to affect generating SQL, but needed for Django admin. Even if so, how do I get desired effect?

My Django version is 1.3.0 final

Answer 1

Note that the default parameter can also take a callable object: https://docs.djangoproject.com/en/dev/ref/models/fields/#default. That is certainly a behavior that cannot be reproduced in SQL! So it would not be possible for Django to generate SQL for every possible case. It looks like for the sake of simplicity and consistency they have chosen not to generate SQL for any case.

Answer 2

The only permanent solution is to patch the Django source, specifically db/backends/creation.py:

Find:

if f.primary_key:
    field_output.append(style.SQL_KEYWORD('PRIMARY KEY'))
elif f.unique:
    field_output.append(style.SQL_KEYWORD('UNIQUE'))

After add:

if(f.default != models.fields.NOT_PROVIDED):
    field_output.append(style.SQL_KEYWORD('DEFAULT ' + str(f.default)))

(Source: http://www.supermind.org/blog/671/django-not-setting-default-column-value-in-mysql)

Alternatively (and preferably), if you're using South, you can just execute some additional SQL after the db.create_table in your migration:

MySQL:

db.execute("ALTER TABLE yourapp_yourmodel MODIFY status int Default '4'")

Postgres:

db.execute("ALTER TABLE yourapp_yourmodel ALTER COLUMN status SET DEFAULT 4")

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