DictionaryField + south schemamigration results in wrong default field value.

[lockwooddev]

I'm using the latest 1.3.0 release and noticed something odd using the DictionaryField and South (0.8.4) schemamigrations.

I have the following field:

stats = hstore.DictionaryField(
    null=True, schema=[{
        'name': 'total', 'class': 'IntegerField', 'kwargs': {'default': 0}}])

Now when I add a schemamigration for this new field, I end up with a wrong default value on the migration:

def forwards(self, orm):
    # Adding field 'User.stats'
    db.add_column(
        u'users_user', 'stats', self.gf(u'django_hstore.fields.DictionaryField')(default={}, null=True), keep_default=False)

Running this migration results in:

DEBUG 2014-08-06 12:51:22,180 django.db.backends (0.000) ALTER TABLE "users_user" ADD COLUMN "stats" hstore NULL DEFAULT ;; args=[]
FATAL ERROR - The following SQL query failed: ALTER TABLE "users_user" ADD COLUMN "stats" hstore NULL DEFAULT ;
The error was: syntax error at or near ";"
LINE 1: ... TABLE "users_user" ADD COLUMN "stats" hstore NULL DEFAULT ;

The default value on the migration should be a None instead of an empty Dict {}.

To fix this I have to change the default value to None in the forwards migration and in the frozen models.

def forwards(self, orm):
    # Adding field 'User.stats'
    db.add_column(
        u'users_user', 'stats', self.gf(u'django_hstore.fields.DictionaryField')(default=None, null=True), keep_default=False)

Do you know what might be causing this?

[nemesifier]

for this reason:
https://github.com/djangonauts/django-hstore/blob/master/django_hstore/fields.py#L104

I seem to remember that it was necessary for the schema mode to work but now I don't remember clearly.

I'll investigate asap

[nemesifier]

removing the forced default does not cause issues.

Setting None as a default value in schema mode does not work and support it would complicate things a bit to no advantage.

Could you verify again with the latest changes?

[lockwooddev]

Removing the forced default does not affect the schemamigration. Maybe something can be done with south to overcome this issue with it's introspection. I will try later this week to come up with something.

[lockwooddev]

As a side note: your commit acd1a9b breaks functionality for me.

models.py:352: in serialize
>           'total': self.total,
../env/src/django-hstore/django_hstore/virtual.py:47: in __get__
>       return getattr(instance, self.hstore_field_name).get(self.name, self.default)
E       AttributeError: 'NoneType' object has no attribute 'get'

test_stats.py:486: in test_conditions_true
>       dummy.total = 1000
../env/src/django-hstore/django_hstore/virtual.py:54: in __set__
>       hstore_dictionary[self.name] = value
E       TypeError: 'NoneType' object does not support item assignment

The default of the DictionaryField is turned into a NoneType object and the VirtualFields in the schema cannot be accessed anymore.

[nemesifier]

that's why the dictionary field should not have default=None, i wrote it in the previous comment

[nemesifier]

This is probably the correct way to fix this:
http://south.readthedocs.org/en/latest/customfields.html
https://github.com/djangonauts/django-hstore/blob/master/django_hstore/fields.py#L69

[nemesifier]

it should be fixed now in the dev version

[nemesifier]

let us know if you encounter other issues.