rest_framework/fields.py

@@ -375,12 +375,13 @@ def bind(self, field_name, parent):
         # In order to enforce a consistent style, we error if a redundant
         # 'source' argument has been used. For example:
         # my_field = serializer.CharField(source='my_field')
-        assert self.source != field_name, (
-            "It is redundant to specify `source='%s'` on field '%s' in "
-            "serializer '%s', because it is the same as the field name. "
-            "Remove the `source` keyword argument." %
-            (field_name, self.__class__.__name__, parent.__class__.__name__)
-        )
+        if field_name == self.source:
+            warnings.warn(
+                "It is redundant to specify `source='%s'` on field '%s' in "
+                "serializer '%s', because it is the same as the field name. "
+                "Remove the `source` keyword argument." %
+                (field_name, self.__class__.__name__, parent.__class__.__name__),
+            )
 
         self.field_name = field_name
         self.parent = parent

rest_framework/generics.py

@@ -21,7 +21,7 @@ def get_object_or_404(queryset, *filter_args, **filter_kwargs):
         raise Http404
 
 
-class GenericAPIView(views.APIView):
+class GenericAPIView(mixins.PaginationMixin, views.APIView):
     """
     Base class for all other generic views.
     """
@@ -42,9 +42,6 @@ class GenericAPIView(views.APIView):
     # The filter backend classes to use for queryset filtering
     filter_backends = api_settings.DEFAULT_FILTER_BACKENDS
 
-    # The style to use for queryset pagination.
-    pagination_class = api_settings.DEFAULT_PAGINATION_CLASS
-
     def get_queryset(self):
         """
         Get the list of items for this view.
@@ -150,33 +147,6 @@ def filter_queryset(self, queryset):
             queryset = backend().filter_queryset(self.request, queryset, self)
         return queryset
 
-    @property
-    def paginator(self):
-        """
-        The paginator instance associated with the view, or `None`.
-        """
-        if not hasattr(self, '_paginator'):
-            if self.pagination_class is None:
-                self._paginator = None
-            else:
-                self._paginator = self.pagination_class()
-        return self._paginator
-
-    def paginate_queryset(self, queryset):
-        """
-        Return a single page of results, or `None` if pagination is disabled.
-        """
-        if self.paginator is None:
-            return None
-        return self.paginator.paginate_queryset(queryset, self.request, view=self)
-
-    def get_paginated_response(self, data):
-        """
-        Return a paginated style `Response` object for the given output data.
-        """
-        assert self.paginator is not None
-        return self.paginator.get_paginated_response(data)
-
 
 # Concrete view classes that provide method handlers
 # by composing the mixin classes with the base view.

rest_framework/mixins.py

@@ -30,6 +30,41 @@ def get_success_headers(self, data):
             return {}
 
 
+class PaginationMixin(object):
+    """
+    Adds pagination methods to a view.
+    """
+    # The style to use for queryset pagination.
+    pagination_class = api_settings.DEFAULT_PAGINATION_CLASS
+
+    @property
+    def paginator(self):
+        """
+        The paginator instance associated with the view, or `None`.
+        """
+        if not hasattr(self, '_paginator'):
+            if self.pagination_class is None:
+                self._paginator = None
+            else:
+                self._paginator = self.pagination_class()
+        return self._paginator
+
+    def get_paginated_response(self, data):
+        """
+        Return a paginated style `Response` object for the given output data.
+        """
+        assert self.paginator is not None
+        return self.paginator.get_paginated_response(data)
+
+    def paginate_queryset(self, queryset):
+        """
+        Return a single page of results, or `None` if pagination is disabled.
+        """
+        if self.paginator is None:
+            return None
+        return self.paginator.paginate_queryset(queryset, self.request, view=self)
+
+
 class ListModelMixin:
     """
     List a queryset.

rest_framework/relations.py

@@ -1,4 +1,5 @@
 import sys
+import warnings
 from collections import OrderedDict
 from urllib import parse
 
@@ -108,10 +109,11 @@ def __init__(self, **kwargs):
                 'Relational field must provide a `queryset` argument, '
                 'override `get_queryset`, or set read_only=`True`.'
             )
-        assert not (self.queryset is not None and kwargs.get('read_only')), (
-            'Relational fields should not provide a `queryset` argument, '
-            'when setting read_only=`True`.'
-        )
+        if self.queryset is not None and kwargs.get('read_only'):
+            warnings.warn(
+                'Relational fields should not provide a `queryset` argument, '
+                'when setting read_only=`True`.'
+            )
         kwargs.pop('many', None)
         kwargs.pop('allow_empty', None)
         super().__init__(**kwargs)

tests/test_fields.py

@@ -186,9 +186,10 @@ class ExampleSerializer(serializers.Serializer):
     def test_redundant_source(self):
         class ExampleSerializer(serializers.Serializer):
             example_field = serializers.CharField(source='example_field')
-        with pytest.raises(AssertionError) as exc_info:
+        with pytest.warns(UserWarning) as record:
             ExampleSerializer().fields
-        assert str(exc_info.value) == (
+        assert len(record) == 1
+        assert record[0].message.args[0] == (
             "It is redundant to specify `source='example_field'` on field "
             "'CharField' in serializer 'ExampleSerializer', because it is the "
             "same as the field name. Remove the `source` keyword argument."