Allow HStoreField to store null values in key: value pairs

[David Hoffman]

Overview

PostgreSQL allows values to be either strings or nulls in hstore: ​https://www.postgresql.org/docs/9.5/static/hstore.html

It appears that the form and model HStoreFields do not support null values. Is this something that should be fixed?

How to reproduce for the form field

>>> from django.contrib.postgres import forms
>>> field = forms.HStoreField()
>>> field.clean('{"a": null}')
{u'a': u'None'} 

Expected Behavior

The null has been converted to a string, when it should actually be the None value

How to reproduce for the model field

>>> from django.contrib.postgres.fields import HStoreField
>>> field = HStoreField()
>>> field.clean({'a': None}, None)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/Users/dhoffman/.envs/brain-campaign/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 588, in clean
    self.validate(value, model_instance)
  File "/Users/dhoffman/.envs/brain-campaign/lib/python2.7/site-packages/django/contrib/postgres/fields/hstore.py", line 36, in validate
    params={'key': key},
ValidationError: [u'The value of "a" is not a string.']

Expected Behavior

This should actually be allowed without error.

[David Hoffman]

I have opened a pull request at ​https://github.com/django/django/pull/7668

[Tim Graham]

Marc, did you make a conscious design decision about this when you first implemented the field?

[Marc Tamlyn]

Not that I recall. This use case should be valid.

[Tim Graham <timograham@…>]

In bf84d04:

Fixed #27582 -- Allowed HStoreField to store null values.