Port get_schema_fields from DRF

django_filters/rest_framework/backends.py

@@ -2,7 +2,7 @@
 from __future__ import absolute_import
 
 from django.template import Template, TemplateDoesNotExist, loader
-from rest_framework.compat import template_render
+from rest_framework.compat import coreapi, template_render
 from rest_framework.filters import BaseFilterBackend
 
 from .. import compat
@@ -89,3 +89,15 @@ class DjangoFilterBackend(BaseFilterBackend):
         return template_render(template, context={
             'filter': filter_instance
         })
+
+    def get_schema_fields(self, view):
+        # This is not compatible with widgets where the query param differs from the
+        # filter's attribute name. Notably, this includes `MultiWidget`, where query
+        # params will be of the format `<name>_0`, `<name>_1`, etc...
+        assert coreapi is not None, 'coreapi must be installed to use `get_schema_fields()`'
+        filter_class = self.get_filter_class(view, view.get_queryset())
+
+        return [] if not filter_class else [
+            coreapi.Field(name=field_name, required=False, location='query')
+            for field_name in filter_class().filters.keys()
+        ]

tests/rest_framework/test_backends.py

@@ -2,6 +2,7 @@ from __future__ import unicode_literals
 
 import datetime
 from decimal import Decimal
+from unittest import skipIf
 
 from django.conf.urls import url
 from django.test import TestCase
@@ -15,6 +16,7 @@ except ImportError:
     from django.core.urlresolvers import reverse
 
 from rest_framework import generics, serializers, status
+from rest_framework.compat import coreapi
 from rest_framework.test import APIRequestFactory
 
 from django_filters import filters
@@ -121,6 +123,35 @@ urlpatterns = [
 ]
 
 
+@skipIf(coreapi is None, 'coreapi must be installed')
+class GetSchemaFieldsTests(TestCase):
+    def test_fields_with_filter_fields_list(self):
+        backend = DjangoFilterBackend()
+        fields = backend.get_schema_fields(FilterFieldsRootView())
+        fields = [f.name for f in fields]
+
+        self.assertEqual(fields, ['decimal', 'date'])
+
+    def test_fields_with_filter_fields_dict(self):
+        class DictFilterFieldsRootView(FilterFieldsRootView):
+            filter_fields = {
+                'decimal': ['exact', 'lt', 'gt'],
+            }
+
+        backend = DjangoFilterBackend()
+        fields = backend.get_schema_fields(DictFilterFieldsRootView())
+        fields = [f.name for f in fields]
+
+        self.assertEqual(fields, ['decimal', 'decimal__lt', 'decimal__gt'])
+
+    def test_fields_with_filter_class(self):
+        backend = DjangoFilterBackend()
+        fields = backend.get_schema_fields(FilterClassRootView())
+        fields = [f.name for f in fields]
+
+        self.assertEqual(fields, ['text', 'decimal', 'date'])
+
+
 class CommonFilteringTestCase(TestCase):
     def _serialize_object(self, obj):
         return {'id': obj.id, 'text': obj.text, 'decimal': str(obj.decimal), 'date': obj.date.isoformat()}