Raise warnings if 'request' not in context for hyperlinked fields.

rest_framework/relations.py

@@ -311,6 +311,13 @@ class HyperlinkedRelatedField(RelatedField):
         view_name = self.view_name
         request = self.context.get('request', None)
         format = self.format or self.context.get('format', None)
+
+        if request is None:
+            warnings.warn("Using `HyperlinkedRelatedField` without including the "
+                          "request in the serializer context is due to be deprecated. "
+                          "Add `context={'request': request}` when instantiating the serializer.",
+                          PendingDeprecationWarning, stacklevel=4)
+
         pk = getattr(obj, 'pk', None)
         if pk is None:
             return
@@ -420,6 +427,12 @@ class HyperlinkedIdentityField(Field):
         view_name = self.view_name or self.parent.opts.view_name
         kwargs = {self.pk_url_kwarg: obj.pk}
 
+        if request is None:
+            warnings.warn("Using `HyperlinkedIdentityField` without including the "
+                          "request in the serializer context is due to be deprecated. "
+                          "Add `context={'request': request}` when instantiating the serializer.",
+                          PendingDeprecationWarning, stacklevel=4)
+
         # By default use whatever format is given for the current context
         # unless the target is a different type to the source.
         #