Rm custom __getitem__ method (#30)

jsonattrs/fields.py

@@ -67,7 +67,8 @@ def setup_schema(self, schemas=None):
 
     def _pre_save_selector_check(self, strict=False):
         if not self._setup:
-            self.setup_from_dict(self._db_val)
+            self.setup_from_dict(self._db_val if self._instance._state.adding
+                                 else self._get_from_instance())
         old_selectors = self._saved_selectors
         new_selectors = Schema.objects._get_selectors(self._instance)
         self._saved_selectors = new_selectors
@@ -127,12 +128,6 @@ def _check_key(self, key):
         if key not in self._attrs and key not in self:
             raise KeyError(key)
 
-    def __getitem__(self, key):
-        if not self._setup:
-            self.setup_from_dict(self._db_val)
-        self._check_key(key)
-        return super().__getitem__(key)
-
     def __setitem__(self, key, value):
         if self._init_done:
             self._check_key(key)
@@ -204,14 +199,3 @@ def get_prep_lookup(self, lookup_type, value):
         return (Json(dict(value), dumps=json_serialiser)
                 if isinstance(value, dict)
                 else super().get_prep_lookup(lookup_type, value))
-
-    # def validate(self, value, model_instance):
-    #     super(JSONField, self).validate(value, model_instance)
-    #     try:
-    #         json.dumps(dict(value))
-    #     except TypeError:
-    #         raise exceptions.ValidationError(
-    #             self.error_messages['invalid'],
-    #             code='invalid',
-    #             params={'value': value},
-    #         )

jsonattrs/signals.py

@@ -1,3 +1,5 @@
+import functools
+
 from django.core.exceptions import FieldError
 
 from .fields import JSONAttributes, JSONAttributeField
@@ -31,6 +33,8 @@ def fixup_instance(sender, **kwargs):
 
         # Cache model instance on JSONAttributes instance and vice-versa
         attrs._instance = instance
+        attrs._get_from_instance = functools.partial(
+            getattr, instance, field_name)
         instance._attr_field = attrs
 
     if not hasattr(instance, '_attr_field'):

tests/test_field.py

@@ -4,6 +4,7 @@
 from django.test import TestCase
 from django.core.exceptions import ValidationError
 
+from .factories import OrganizationFactory
 from .fixtures import create_fixtures
 from .models import Organization, Project, Party, Parcel
 from jsonattrs.fields import convert
@@ -187,6 +188,17 @@ def test_attributes_lookup_dict(self):
         assert Party.objects.count() == 45
         assert Party.objects.filter(attrs={'homeowner': 'False'}).count() == 5
 
+    def test_cast_to_dict_with_unknown_attr(self):
+        """
+        Ensure that data with unknown attributes can still be cast to dict.
+        This is used by DRF's JSONRenderer to render models with a
+        JSONAttribute field to JSON.
+        """
+        prj = Organization.objects.bulk_create([  # Skip validation on create
+            OrganizationFactory.build(attrs={'foo': 'bar'})
+        ])[0]
+        assert dict(prj.attrs) == {'foo': 'bar'}
+
 
 class FieldDbTest(FieldTestBase):
     def test_check_fixtures(self):