Added an additional attribute `unknown_form_fields` to `FormResource`

If the attribute is set to `True`, the validation method will not
raise an `ErrorResponse` with status 400 but silently strip out
unexpected fields on the form and only return the validated data.

1 files changed, 11 insertions, 2 deletions

diff --git a/djangorestframework/resources.py b/djangorestframework/resources.py
index 68b285b9..d2651036 100644
--- a/djangorestframework/resources.py
+++ b/djangorestframework/resources.py
@@ -78,13 +78,22 @@ class FormResource(Resource):
     This can be overridden by a :attr:`form` attribute on the :class:`views.View`.
     """
 
+    unknown_form_fields = False
+    """
+    Flag to check for unknown fields when validating a form. If set to false and
+    we receive request data that is not expected by the form it raises an
+    :exc:`response.ErrorResponse` with status code 400. If set to true, only 
+    expected fields are validated.
+    """
+
 
     def validate_request(self, data, files=None):
         """
         Given some content as input return some cleaned, validated content.
         Raises a :exc:`response.ErrorResponse` with status code 400 (Bad Request) on failure.
 
-        Validation is standard form validation, with an additional constraint that *no extra unknown fields* may be supplied.
+        Validation is standard form validation, with an additional constraint that *no extra unknown fields* may be supplied
+        if :attr:`self.unknown_form_fields` is ``True``.
 
         On failure the :exc:`response.ErrorResponse` content is a dict which may contain :obj:`'errors'` and :obj:`'field-errors'` keys.
         If the :obj:`'errors'` key exists it is a list of strings of non-field errors.
@@ -132,7 +141,7 @@ class FormResource(Resource):
         unknown_fields = unknown_fields - set(('csrfmiddlewaretoken', '_accept', '_method'))  # TODO: Ugh.
 
         # Check using both regular validation, and our stricter no additional fields rule
-        if bound_form.is_valid() and not unknown_fields:
+        if bound_form.is_valid() and (self.unknown_form_fields or not unknown_fields):
             # Validation succeeded...
             cleaned_data = bound_form.cleaned_data