When HTML form input is used with JSONField, treat the input as a JSON encoded…

When HTML form input is used with JSONField, treat the input as a JSON encoded string, not a JSON primative. (#4565)

rest_framework/fields.py

@@ -1594,9 +1594,21 @@ class JSONField(Field):
         self.binary = kwargs.pop('binary', False)
         super(JSONField, self).__init__(*args, **kwargs)
 
+    def get_value(self, dictionary):
+        if html.is_html_input(dictionary) and self.field_name in dictionary:
+            # When HTML form input is used, mark up the input
+            # as being a JSON string, rather than a JSON primative.
+            class JSONString(six.text_type):
+                def __new__(self, value):
+                    ret = six.text_type.__new__(self, value)
+                    ret.is_json_string = True
+                    return ret
+            return JSONString(dictionary[self.field_name])
+        return dictionary.get(self.field_name, empty)
+
     def to_internal_value(self, data):
         try:
-            if self.binary:
+            if self.binary or getattr(data, 'is_json_string', False):
                 if isinstance(data, six.binary_type):
                     data = data.decode('utf-8')
                 return json.loads(data)

tests/test_fields.py

@@ -1756,6 +1756,19 @@ class TestJSONField(FieldValues):
     ]
     field = serializers.JSONField()
 
+    def test_html_input_as_json_string(self):
+        """
+        HTML inputs should be treated as a serialized JSON string.
+        """
+        class TestSerializer(serializers.Serializer):
+            config = serializers.JSONField()
+
+        data = QueryDict(mutable=True)
+        data.update({'config': '{"a":1}'})
+        serializer = TestSerializer(data=data)
+        assert serializer.is_valid()
+        assert serializer.validated_data == {'config': {"a": 1}}
+
 
 class TestBinaryJSONField(FieldValues):
     """