Implement database routers

rest_framework/db_routers.py

@@ -0,0 +1,12 @@
+from django.db import router
+
+
+class BaseDbRouter(object):
+    def get_db_alias(self, request, model):
+        raise NotImplementedError(".get_db_alias() must be overridden.")
+
+
+class DjangoDbRouter(BaseDbRouter):
+    def get_db_alias(self, request, model):
+        if request.method.lower() != "get":
+            return router.db_for_write(model)

rest_framework/generics.py

@@ -46,6 +46,9 @@ class GenericAPIView(views.APIView):
     # The style to use for queryset pagination.
     pagination_class = api_settings.DEFAULT_PAGINATION_CLASS
 
+    # The database router classes to use as queryset aliases
+    db_router_classes = api_settings.DEFAULT_DB_ROUTER_CLASSES
+
     def get_queryset(self):
         """
         Get the list of items for this view.
@@ -71,8 +74,19 @@ class GenericAPIView(views.APIView):
         if isinstance(queryset, QuerySet):
             # Ensure queryset is re-evaluated on each request.
             queryset = queryset.all()
+
+        return self.apply_db_routing(queryset)
+
+    def apply_db_routing(self, queryset):
+        for router in self.get_db_routers():
+            alias = router.get_db_alias(self.request, queryset.model)
+            if alias:
+                return queryset.using(alias)
         return queryset
 
+    def get_db_routers(self):
+        return [db_router() for db_router in self.db_router_classes]
+
     def get_object(self):
         """
         Returns the object the view is displaying.

rest_framework/settings.py

@@ -54,6 +54,7 @@ DEFAULTS = {
     # Generic view behavior
     'DEFAULT_PAGINATION_CLASS': 'rest_framework.pagination.PageNumberPagination',
     'DEFAULT_FILTER_BACKENDS': (),
+    'DEFAULT_DB_ROUTER_CLASSES': [],
 
     # Throttling
     'DEFAULT_THROTTLE_RATES': {
@@ -137,7 +138,8 @@ IMPORT_STRINGS = (
     'DEFAULT_METADATA_CLASS',
     'DEFAULT_VERSIONING_CLASS',
     'DEFAULT_PAGINATION_CLASS',
-    'DEFAULT_FILTER_BACKENDS',
+    'DEFAULT_FILTER_BACKENDS'
+    'DEFAULT_DB_ROUTER_CLASSES',
     'EXCEPTION_HANDLER',
     'TEST_REQUEST_RENDERER_CLASSES',
     'UNAUTHENTICATED_USER',

tests/test_db_routers.py

@@ -0,0 +1,66 @@
+from django.test import TestCase
+
+from rest_framework import db_routers, generics
+from rest_framework.test import APIRequestFactory
+
+from .models import BasicModel
+
+
+class NoRoutersView(generics.GenericAPIView):
+    db_router_classes = []
+    queryset = BasicModel.objects.all()
+
+
+class DjangoRouterView(generics.GenericAPIView):
+    db_router_classes = [db_routers.DjangoDbRouter]
+    queryset = BasicModel.objects.all()
+
+
+class Router(object):
+    def db_for_read(self, model, **hints):
+        return 'db_for_read'
+
+    def db_for_write(self, model, **hints):
+        return 'db_for_write'
+
+
+class BaseRoutersTest(TestCase):
+    def setUp(self):
+        self.factory = APIRequestFactory()
+
+    def assertViewUsesAliasForQuerySet(self, view_class, http_method, db_alias):
+        with self.settings(DATABASE_ROUTERS=['tests.test_db_routers.Router']):
+            request = getattr(self.factory, http_method)('/')
+            view = view_class()
+            view.request = request
+
+            queryset = view.get_queryset()
+            self.assertEqual(queryset._db, db_alias)
+
+
+class TestNoDbRouters(BaseRoutersTest):
+    def test_get(self):
+        self.assertViewUsesAliasForQuerySet(NoRoutersView, http_method='get', db_alias=None)
+
+    def test_post(self):
+        self.assertViewUsesAliasForQuerySet(NoRoutersView, http_method='post', db_alias=None)
+
+    def test_put(self):
+        self.assertViewUsesAliasForQuerySet(NoRoutersView, http_method='put', db_alias=None)
+
+    def test_patch(self):
+        self.assertViewUsesAliasForQuerySet(NoRoutersView, http_method='patch', db_alias=None)
+
+
+class TestDjangoDbRouter(BaseRoutersTest):
+    def test_get(self):
+        self.assertViewUsesAliasForQuerySet(DjangoRouterView, http_method='get', db_alias=None)
+
+    def test_post(self):
+        self.assertViewUsesAliasForQuerySet(DjangoRouterView, http_method='post', db_alias='db_for_write')
+
+    def test_put(self):
+        self.assertViewUsesAliasForQuerySet(DjangoRouterView, http_method='put', db_alias='db_for_write')
+
+    def test_patch(self):
+        self.assertViewUsesAliasForQuerySet(DjangoRouterView, http_method='patch', db_alias='db_for_write')