Expand pagination support, add docs

docs/api-guide/pagination.md

@@ -0,0 +1,98 @@
+<a class="github" href="pagination.py"></a>
+
+# Pagination
+
+> Django provides a few classes that help you manage paginated data – that is, data that’s split across several pages, with “Previous/Next” links.
+>
+> &mdash; [Django documentation][cite]
+
+REST framework includes a `PaginationSerializer` class that makes it easy to return paginated data in a way that can then be rendered to arbitrary media types. 
+
+## Examples
+
+Let's start by taking a look at an example from the Django documentation.
+
+    from django.core.paginator import Paginator
+    objects = ['john', 'paul', 'george', 'ringo']
+    paginator = Paginator(objects, 2)
+    page = paginator.page(1)
+    page.object_list
+    # ['john', 'paul']
+
+At this point we've got a page object.  If we wanted to return this page object as a JSON response, we'd need to provide the client with context such as next and previous links, so that it would be able to page through the remaining results.
+
+    from rest_framework.pagination import PaginationSerializer
+    serializer = PaginationSerializer(instance=page)
+    serializer.data
+    # {'count': 4, 'next': '?page=2', 'previous': None, 'results': [u'john', u'paul']}
+
+The `context` argument of the `PaginationSerializer` class may optionally include the request.  If the request is included in the context then the next and previous links returned by the serializer will use absolute URLs instead of relative URLs.
+
+    request = RequestFactory().get('/foobar')
+    serializer = PaginationSerializer(instance=page, context={'request': request})
+    serializer.data
+    # {'count': 4, 'next': 'http://testserver/foobar?page=2', 'previous': None, 'results': [u'john', u'paul']}    
+
+We could now return that data in a `Response` object, and it would be rendered into the correct media type.
+
+Our first example worked because we were using primative objects.  If we wanted to paginate a queryset or other complex data, we'd need to specify a serializer to use to serialize the result set itself with.
+
+We can do this using the `object_serializer_class` attribute on the inner `Meta` class of the pagination serializer.  For example.
+
+    class UserSerializer(serializers.ModelSerializer):
+        """
+        Serializes user querysets.
+        """
+        class Meta:
+            model = User
+            fields = ('username', 'email')
+
+    class PaginatedUserSerializer(pagination.PaginationSerializer):
+        """
+        Serializes page objects of user querysets.
+        """
+        class Meta:
+            object_serializer_class = UserSerializer
+
+    queryset = User.objects.all()
+    paginator = Paginator(queryset, 20)
+    page = paginator.page(1)
+    serializer = PaginatedUserSerializer(instance=page)
+    serializer.data
+    # {'count': 1, 'next': None, 'previous': None, 'results': [{'username': u'admin', 'email': u'admin@example.com'}]}
+
+## Pagination in the generic views
+
+The generic class based views `ListAPIView` and `ListCreateAPIView` provide pagination of the returned querysets by default.  You can customise this behaviour by altering the pagination style, by modifying the default number of results, or by turning pagination off completely.
+
+## Setting the default pagination style
+
+The default pagination style may be set globally, using the `PAGINATION_SERIALIZER` and `PAGINATE_BY` settings.  For example.
+
+    REST_FRAMEWORK = {
+        'PAGINATION_SERIALIZER': (
+            'example_app.pagination.CustomPaginationSerializer',
+        ),
+        'PAGINATE_BY': 10
+    }
+
+You can also set the pagination style on a per-view basis, using the `ListAPIView` generic class-based view.
+
+    class PaginatedListView(ListAPIView):
+        model = ExampleModel
+        pagination_serializer_class = CustomPaginationSerializer
+        paginate_by = 10
+
+## Creating custom pagination serializers
+
+Override `pagination.BasePaginationSerializer`, and set the fields that you want the serializer to return.
+
+For example.
+
+    class CustomPaginationSerializer(pagination.BasePaginationSerializer):
+        next = pagination.NextURLField()
+        total_results = serializers.Field(source='paginator.count')
+
+
+[cite]: https://docs.djangoproject.com/en/dev/topics/pagination/
+

rest_framework/fields.py

@@ -158,6 +158,8 @@ class Field(object):
             return value
         elif hasattr(self, 'model_field'):
             return self.model_field.value_to_string(self.obj)
+        elif hasattr(value, '__iter__') and not isinstance(value, (dict, basestring)):
+            return [self.to_native(item) for item in value]
         return smart_unicode(value)
 
     def attributes(self):

rest_framework/generics.py

@@ -16,20 +16,24 @@ class BaseView(views.APIView):
     """
     serializer_class = None
     model_serializer_class = api_settings.MODEL_SERIALIZER
-    pagination_serializer_class = api_settings.PAGINATION_SERIALIZER
-    paginate_by = api_settings.PAGINATE_BY
 
     def get_serializer_context(self):
+        """
+        Extra context provided to the serializer class.
+        """
         return {
             'request': self.request,
-            'format': self.kwargs.get('format', None)
+            'format': self.format,
+            'view': self
         }
 
-    def get_serializer(self, data=None, files=None, instance=None, kwargs=None):
-        # TODO: add support for files
-        # TODO: add support for seperate serializer/deserializer
+    def get_serializer_class(self):
+        """
+        Return the class to use for the serializer.
+        Use `self.serializer_class`, falling back to constructing a
+        model serializer class from `self.model_serializer_class`
+        """
         serializer_class = self.serializer_class
-        kwargs = kwargs or {}
 
         if serializer_class is None:
             class DefaultSerializer(self.model_serializer_class):
@@ -37,22 +41,38 @@ class BaseView(views.APIView):
                     model = self.model
             serializer_class = DefaultSerializer
 
-        context = self.get_serializer_context()
-        return serializer_class(data, instance=instance, context=context, **kwargs)
+        return serializer_class
 
-    def get_pagination_serializer(self, page=None):
-        serializer_class = self.pagination_serializer_class
+    def get_serializer(self, data=None, files=None, instance=None):
+        # TODO: add support for files
+        # TODO: add support for seperate serializer/deserializer
+        serializer_class = self.get_serializer_class()
         context = self.get_serializer_context()
-        ret = serializer_class(instance=page, context=context)
-        ret.fields['results'] = self.get_serializer(kwargs={'source': 'object_list'})
-        return ret
+        return serializer_class(data, instance=instance, context=context)
 
 
 class MultipleObjectBaseView(MultipleObjectMixin, BaseView):
     """
     Base class for generic views onto a queryset.
     """
-    pass
+
+    pagination_serializer_class = api_settings.PAGINATION_SERIALIZER
+    paginate_by = api_settings.PAGINATE_BY
+
+    def get_pagination_serializer_class(self):
+        """
+        Return the class to use for the pagination serializer.
+        """
+        class SerializerClass(self.pagination_serializer_class):
+            class Meta:
+                object_serializer_class = self.get_serializer_class()
+
+        return SerializerClass
+
+    def get_pagination_serializer(self, page=None):
+        pagination_serializer_class = self.get_pagination_serializer_class()
+        context = self.get_serializer_context()
+        return pagination_serializer_class(instance=page, context=context)
 
 
 class SingleObjectBaseView(SingleObjectMixin, BaseView):

rest_framework/pagination.py

@@ -4,27 +4,64 @@ from rest_framework import serializers
 
 
 class NextPageField(serializers.Field):
+    """
+    Field that returns a link to the next page in paginated results.
+    """
     def to_native(self, value):
         if not value.has_next():
             return None
         page = value.next_page_number()
-        request = self.context['request']
-        return request.build_absolute_uri('?page=%d' % page)
+        request = self.context.get('request')
+        relative_url = '?page=%d' % page
+        if request:
+            return request.build_absolute_uri(relative_url)
+        return relative_url
 
 
 class PreviousPageField(serializers.Field):
+    """
+    Field that returns a link to the previous page in paginated results.
+    """
     def to_native(self, value):
         if not value.has_previous():
             return None
         page = value.previous_page_number()
-        request = self.context['request']
-        return request.build_absolute_uri('?page=%d' % page)
+        request = self.context.get('request')
+        relative_url = '?page=%d' % page
+        if request:
+            return request.build_absolute_uri('?page=%d' % page)
+        return relative_url
 
 
-class PaginationSerializer(serializers.Serializer):
-    count = serializers.Field(source='paginator.count')
-    next = NextPageField(source='*')
-    previous = PreviousPageField(source='*')
+class PaginationSerializerOptions(serializers.SerializerOptions):
+    """
+    An object that stores the options that may be provided to a
+    pagination serializer by using the inner `Meta` class.
+
+    Accessible on the instance as `serializer.opts`.
+    """
+    def __init__(self, meta):
+        super(PaginationSerializerOptions, self).__init__(meta)
+        self.object_serializer_class = getattr(meta, 'object_serializer_class',
+                                               serializers.Field)
+
+
+class BasePaginationSerializer(serializers.Serializer):
+    """
+    A base class for pagination serializers to inherit from,
+    to make implementing custom serializers more easy.
+    """
+    _options_class = PaginationSerializerOptions
+    _results_field = 'results'
+
+    def __init__(self, *args, **kwargs):
+        """
+        Override init to add in the object serializer field on-the-fly.
+        """
+        super(BasePaginationSerializer, self).__init__(*args, **kwargs)
+        results_field = self._results_field
+        object_serializer = self.opts.object_serializer_class
+        self.fields[results_field] = object_serializer(source='object_list')
 
     def to_native(self, obj):
         """
@@ -32,3 +69,12 @@ class PaginationSerializer(serializers.Serializer):
         each in turn.
         """
         return self.convert_object(obj)
+
+
+class PaginationSerializer(BasePaginationSerializer):
+    """
+    A default implementation of a pagination serializer.
+    """
+    count = serializers.Field(source='paginator.count')
+    next = NextPageField(source='*')
+    previous = PreviousPageField(source='*')

rest_framework/serializers.py

@@ -70,7 +70,7 @@ class SerializerMetaclass(type):
 
 class SerializerOptions(object):
     """
-    Meta class options for ModelSerializer
+    Meta class options for Serializer
     """
     def __init__(self, meta):
         self.nested = getattr(meta, 'nested', False)

rest_framework/tests/generics.py

@@ -13,6 +13,7 @@ class RootView(generics.RootAPIView):
     Example description for OPTIONS.
     """
     model = BasicModel
+    paginate_by = None
 
 
 class InstanceView(generics.InstanceAPIView):

rest_framework/tests/pagination.py

@@ -1,6 +1,7 @@
+from django.core.paginator import Paginator
 from django.test import TestCase
 from django.test.client import RequestFactory
-from rest_framework import generics, status
+from rest_framework import generics, status, pagination
 from rest_framework.tests.models import BasicModel
 
 factory = RequestFactory()
@@ -14,7 +15,11 @@ class RootView(generics.RootAPIView):
     paginate_by = 10
 
 
-class TestPaginatedView(TestCase):
+class IntegrationTestPagination(TestCase):
+    """
+    Integration tests for paginated list views.
+    """
+
     def setUp(self):
         """
         Create 26 BasicModel intances.
@@ -55,3 +60,28 @@ class TestPaginatedView(TestCase):
         self.assertEquals(response.data['results'], self.data[20:])
         self.assertEquals(response.data['next'], None)
         self.assertNotEquals(response.data['previous'], None)
+
+
+class UnitTestPagination(TestCase):
+    """
+    Unit tests for pagination of primative objects.
+    """
+
+    def setUp(self):
+        self.objects = [char * 3 for char in 'abcdefghijklmnopqrstuvwxyz']
+        paginator = Paginator(self.objects, 10)
+        self.first_page = paginator.page(1)
+        self.last_page = paginator.page(3)
+
+    def test_native_pagination(self):
+        serializer = pagination.PaginationSerializer(instance=self.first_page)
+        self.assertEquals(serializer.data['count'], 26)
+        self.assertEquals(serializer.data['next'], '?page=2')
+        self.assertEquals(serializer.data['previous'], None)
+        self.assertEquals(serializer.data['results'], self.objects[:10])
+
+        serializer = pagination.PaginationSerializer(instance=self.last_page)
+        self.assertEquals(serializer.data['count'], 26)
+        self.assertEquals(serializer.data['next'], None)
+        self.assertEquals(serializer.data['previous'], '?page=2')
+        self.assertEquals(serializer.data['results'], self.objects[20:])