From a490e99b0320707be0ccfb86c65b954bf4f437d3 Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Thu, 13 Oct 2016 12:00:37 +0100
Subject: [PATCH] Minimal fix that addresses test case

---
 rest_framework/serializers.py         |  2 +-
 rest_framework/utils/field_mapping.py |  2 +-
 rest_framework/utils/model_meta.py    | 15 ++++++++++-----
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 02c21da15..6b0aa32a8 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -1167,7 +1167,7 @@ class ModelSerializer(Serializer):
         field_kwargs = get_relation_kwargs(field_name, relation_info)
 
         to_field = field_kwargs.pop('to_field', None)
-        if to_field and not relation_info.related_model._meta.get_field(to_field).primary_key:
+        if to_field and not relation_info.reverse and not relation_info.related_model._meta.get_field(to_field).primary_key:
             field_kwargs['slug_field'] = to_field
             field_class = self.serializer_related_to_field
 
diff --git a/rest_framework/utils/field_mapping.py b/rest_framework/utils/field_mapping.py
index 64df9a08e..29005f6b7 100644
--- a/rest_framework/utils/field_mapping.py
+++ b/rest_framework/utils/field_mapping.py
@@ -238,7 +238,7 @@ def get_relation_kwargs(field_name, relation_info):
     """
     Creates a default instance of a flat relational field.
     """
-    model_field, related_model, to_many, to_field, has_through_model = relation_info
+    model_field, related_model, to_many, to_field, has_through_model, reverse = relation_info
     kwargs = {
         'queryset': related_model._default_manager,
         'view_name': get_detail_view_name(related_model)
diff --git a/rest_framework/utils/model_meta.py b/rest_framework/utils/model_meta.py
index 94aa46e72..3e3e434e6 100644
--- a/rest_framework/utils/model_meta.py
+++ b/rest_framework/utils/model_meta.py
@@ -23,7 +23,8 @@ RelationInfo = namedtuple('RelationInfo', [
     'related_model',
     'to_many',
     'to_field',
-    'has_through_model'
+    'has_through_model',
+    'reverse'
 ])
 
 
@@ -81,7 +82,8 @@ def _get_forward_relationships(opts):
             related_model=get_related_model(field),
             to_many=False,
             to_field=_get_to_field(field),
-            has_through_model=False
+            has_through_model=False,
+            reverse=False
         )
 
     # Deal with forward many-to-many relationships.
@@ -94,7 +96,8 @@ def _get_forward_relationships(opts):
             to_field=None,
             has_through_model=(
                 not get_remote_field(field).through._meta.auto_created
-            )
+            ),
+            reverse=False
         )
 
     return forward_relations
@@ -118,7 +121,8 @@ def _get_reverse_relationships(opts):
             related_model=related,
             to_many=get_remote_field(relation.field).multiple,
             to_field=_get_to_field(relation.field),
-            has_through_model=False
+            has_through_model=False,
+            reverse=True
         )
 
     # Deal with reverse many-to-many relationships.
@@ -135,7 +139,8 @@ def _get_reverse_relationships(opts):
             has_through_model=(
                 (getattr(get_remote_field(relation.field), 'through', None) is not None) and
                 not get_remote_field(relation.field).through._meta.auto_created
-            )
+            ),
+            reverse=True
         )
 
     return reverse_relations