Merge pull request #412 from minddust/custom_page_size_per_request

support for custom page size per request

3 files changed, 158 insertions, 2 deletions

diff --git a/rest_framework/mixins.py b/rest_framework/mixins.py
index 53c4d984..0da4c2cc 100644
--- a/rest_framework/mixins.py
+++ b/rest_framework/mixins.py
@@ -7,6 +7,7 @@ which allows mixin classes to be composed in interesting ways.
 from django.http import Http404
 from rest_framework import status
 from rest_framework.response import Response
+from rest_framework.settings import api_settings
 
 
 class CreateModelMixin(object):
@@ -39,6 +40,7 @@ class ListModelMixin(object):
     Should be mixed in with `MultipleObjectAPIView`.
     """
     empty_error = u"Empty list and '%(class_name)s.allow_empty' is False."
+    page_size_kwarg = api_settings.PAGE_SIZE_KWARG
 
     def list(self, request, *args, **kwargs):
         queryset = self.get_queryset()
@@ -64,6 +66,17 @@ class ListModelMixin(object):
 
         return Response(serializer.data)
 
+    def get_paginate_by(self, queryset):
+        if self.page_size_kwarg is not None:
+            page_size_kwarg = self.request.QUERY_PARAMS.get(self.page_size_kwarg)
+            if page_size_kwarg:
+                try:
+                    page_size = int(page_size_kwarg)
+                    return page_size
+                except ValueError:
+                    pass
+        return super(ListModelMixin, self).get_paginate_by(queryset)
+
 
 class RetrieveModelMixin(object):
     """
diff --git a/rest_framework/settings.py b/rest_framework/settings.py
index 4f10481d..8883b963 100644
--- a/rest_framework/settings.py
+++ b/rest_framework/settings.py
@@ -66,7 +66,9 @@ DEFAULTS = {
     'URL_ACCEPT_OVERRIDE': 'accept',
     'URL_FORMAT_OVERRIDE': 'format',
 
-    'FORMAT_SUFFIX_KWARG': 'format'
+    'FORMAT_SUFFIX_KWARG': 'format',
+
+    'PAGE_SIZE_KWARG': 'page_size'
 }
 
 
diff --git a/rest_framework/tests/pagination.py b/rest_framework/tests/pagination.py
index 713a7255..8aae2147 100644
--- a/rest_framework/tests/pagination.py
+++ b/rest_framework/tests/pagination.py
@@ -34,6 +34,29 @@ if django_filters:
         filter_backend = filters.DjangoFilterBackend
 
 
+class DefaultPageSizeKwargView(generics.ListAPIView):
+    """
+    View for testing default page_size usage
+    """
+    model = BasicModel
+
+
+class CustomPageSizeKwargView(generics.ListAPIView):
+    """
+    View for testing custom page_size usage
+    """
+    model = BasicModel
+    page_size_kwarg = 'ps'
+
+
+class NonePageSizeKwargView(generics.ListAPIView):
+    """
+    View for testing None page_size usage
+    """
+    model = BasicModel
+    page_size_kwarg = None
+
+
 class IntegrationTestPagination(TestCase):
     """
     Integration tests for paginated list views.
@@ -135,7 +158,7 @@ class IntegrationTestPaginationAndFiltering(TestCase):
 
 class UnitTestPagination(TestCase):
     """
-    Unit tests for pagination of primative objects.
+    Unit tests for pagination of primitive objects.
     """
 
     def setUp(self):
@@ -156,3 +179,121 @@ class UnitTestPagination(TestCase):
         self.assertEquals(serializer.data['next'], None)
         self.assertEquals(serializer.data['previous'], '?page=2')
         self.assertEquals(serializer.data['results'], self.objects[20:])
+
+
+class TestDefaultPageSizeKwarg(TestCase):
+    """
+    Tests for list views with default page size kwarg
+    """
+
+    def setUp(self):
+        """
+        Create 13 BasicModel instances.
+        """
+        for i in range(13):
+            BasicModel(text=i).save()
+        self.objects = BasicModel.objects
+        self.data = [
+        {'id': obj.id, 'text': obj.text}
+        for obj in self.objects.all()
+        ]
+        self.view = DefaultPageSizeKwargView.as_view()
+
+    def test_default_page_size(self):
+        """
+        Tests the default page size for this view.
+        no page size --> no limit --> no meta data
+        """
+        request = factory.get('/')
+        response = self.view(request).render()
+        self.assertEquals(response.data, self.data)
+
+    def test_default_page_size_kwarg(self):
+        """
+        If page_size_kwarg is set not set, the default page_size kwarg should limit per view requests.
+        """
+        request = factory.get('/?page_size=5')
+        response = self.view(request).render()
+        self.assertEquals(response.data['count'], 13)
+        self.assertEquals(response.data['results'], self.data[:5])
+
+
+class TestCustomPageSizeKwarg(TestCase):
+    """
+    Tests for list views with default page size kwarg
+    """
+
+    def setUp(self):
+        """
+        Create 13 BasicModel instances.
+        """
+        for i in range(13):
+            BasicModel(text=i).save()
+        self.objects = BasicModel.objects
+        self.data = [
+        {'id': obj.id, 'text': obj.text}
+        for obj in self.objects.all()
+        ]
+        self.view = CustomPageSizeKwargView.as_view()
+
+    def test_default_page_size(self):
+        """
+        Tests the default page size for this view.
+        no page size --> no limit --> no meta data
+        """
+        request = factory.get('/')
+        response = self.view(request).render()
+        self.assertEquals(response.data, self.data)
+
+    def test_disabled_default_page_size_kwarg(self):
+        """
+        If page_size_kwarg is set set, the default page_size kwarg should not work.
+        """
+        request = factory.get('/?page_size=5')
+        response = self.view(request).render()
+        self.assertEquals(response.data, self.data)
+
+    def test_custom_page_size_kwarg(self):
+        """
+        If page_size_kwarg is set set, the new kwarg should limit per view requests.
+        """
+        request = factory.get('/?ps=5')
+        response = self.view(request).render()
+        self.assertEquals(response.data['count'], 13)
+        self.assertEquals(response.data['results'], self.data[:5])
+
+
+class TestNonePageSizeKwarg(TestCase):
+    """
+    Tests for list views with default page size kwarg
+    """
+
+    def setUp(self):
+        """
+        Create 13 BasicModel instances.
+        """
+        for i in range(13):
+            BasicModel(text=i).save()
+        self.objects = BasicModel.objects
+        self.data = [
+        {'id': obj.id, 'text': obj.text}
+        for obj in self.objects.all()
+        ]
+        self.view = NonePageSizeKwargView.as_view()
+
+    def test_default_page_size(self):
+        """
+        Tests the default page size for this view.
+        no page size --> no limit --> no meta data
+        """
+        request = factory.get('/')
+        response = self.view(request).render()
+        self.assertEquals(response.data, self.data)
+
+    def test_none_page_size_kwarg(self):
+        """
+        If page_size_kwarg is set to None, custom page_size per request should be disabled.
+        """
+        request = factory.get('/?page_size=5')
+        response = self.view(request).render()
+        self.assertEquals(response.data, self.data)