Django 3.1 adds a new generic JSONField to replace the PostgreSQL-specific one. This adds support for the new field type, which should behave the same as the existing PostgreSQL field.
Django's new JSONField also includes support for a custom "decoder", so add support for that in the serializer field.
* Make `NullBooleanField` subclass `BooleanField`
This removes a lot of the redundancy that was in place becuase we
were not doing this. This maintains the `None` initial value that
was previously present, as well as disallowing `allow_null` to be
passed in.
* Remove special case for mapping `NullBooleanField`
In newer versions of Django, the `NullBooleanField` is handled the
same way as a `BooleanField(null=True)`. Given that we also support
that combination, and that our own `NullBooleanField` behaves in the
same manner, it makes sense to remove the special casing that exists
for it.
* Add test for BooleanField(null=True, choices)
* Remove special case for NullBooleanField
* Adjust mapping tests for NullBooleanField
* Fixed linting error
* Raise deprecation warning when NullBooleanField is used
* Fix linting issue in imports
* Fix ModelSerializer unique_together field sources
Updates ModelSerializer to check for serializer fields that map to the
model field sources in the unique_together lists.
* Ensure field name ordering consistency
* Pass data via response instead of renderer_context
Instead of relying on internal implementation details to get a reference
to the response or view, attach these directly to the returned response.
* Remove unused method
* SearchFilter to support Custom query Transforms
Since Some fields support `__` as a custom Transform for query lookups we needed to update the m2m checking code to handle search_fields that contain __ that are not relationships.
* Update documentation on SearchFilter to include references to JSON and HStore Fields.
The `maximum` is valid here within the schema but it was not
previously being included because we were not copying over the
entire schema for the generated `IntegerField` previously.
The `ListField` was generating a schema that contained `type=None`
when a `ChoiceField` was the child, since we are not currently able
to introspect the type of a `ChoiceField`.
