Fix schemas for extra actions (#5992)

* Add failing test for extra action schemas

* Add ViewInspector setter to store instances

* Fix schema disabling for extra actions

* Add docs note about disabling schemas for actions

docs/api-guide/schemas.md

@@ -243,6 +243,14 @@ You may disable schema generation for a view by setting `schema` to `None`:
             ...
             schema = None  # Will not appear in schema
 
+This also applies to extra actions for `ViewSet`s:
+
+        class CustomViewSet(viewsets.ModelViewSet):
+
+            @action(detail=True, schema=None)
+            def extra_action(self, request, pk=None):
+                ...
+
 ---
 
 **Note**: For full details on `SchemaGenerator` plus the `AutoSchema` and

rest_framework/schemas/generators.py

@@ -218,6 +218,10 @@ class EndpointEnumerator(object):
         if callback.cls.schema is None:
             return False
 
+        if 'schema' in callback.initkwargs:
+            if callback.initkwargs['schema'] is None:
+                return False
+
         if path.endswith('.{format}') or path.endswith('.{format}/'):
             return False  # Ignore .json style URLs.
 
@@ -365,9 +369,7 @@ class SchemaGenerator(object):
         """
         Given a callback, return an actual view instance.
         """
-        view = callback.cls()
-        for attr, val in getattr(callback, 'initkwargs', {}).items():
-            setattr(view, attr, val)
+        view = callback.cls(**getattr(callback, 'initkwargs', {}))
         view.args = ()
         view.kwargs = {}
         view.format_kwarg = None

rest_framework/schemas/inspectors.py

@@ -7,6 +7,7 @@ See schemas.__init__.py for package overview.
 import re
 import warnings
 from collections import OrderedDict
+from weakref import WeakKeyDictionary
 
 from django.db import models
 from django.utils.encoding import force_text, smart_text
@@ -128,6 +129,10 @@ class ViewInspector(object):
 
     Provide subclass for per-view schema generation
     """
+
+    def __init__(self):
+        self.instance_schemas = WeakKeyDictionary()
+
     def __get__(self, instance, owner):
         """
         Enables `ViewInspector` as a Python _Descriptor_.
@@ -144,9 +149,17 @@ class ViewInspector(object):
         See: https://docs.python.org/3/howto/descriptor.html for info on
         descriptor usage.
         """
+        if instance in self.instance_schemas:
+            return self.instance_schemas[instance]
+
         self.view = instance
         return self
 
+    def __set__(self, instance, other):
+        self.instance_schemas[instance] = other
+        if other is not None:
+            other.view = instance
+
     @property
     def view(self):
         """View property."""
@@ -189,6 +202,7 @@ class AutoSchema(ViewInspector):
         * `manual_fields`: list of `coreapi.Field` instances that
             will be added to auto-generated fields, overwriting on `Field.name`
         """
+        super(AutoSchema, self).__init__()
         if manual_fields is None:
             manual_fields = []
         self._manual_fields = manual_fields
@@ -455,6 +469,7 @@ class ManualSchema(ViewInspector):
         * `fields`: list of `coreapi.Field` instances.
         * `descripton`: String description for view. Optional.
         """
+        super(ManualSchema, self).__init__()
         assert all(isinstance(f, coreapi.Field) for f in fields), "`fields` must be a list of coreapi.Field instances"
         self._fields = fields
         self._description = description
@@ -474,9 +489,13 @@ class ManualSchema(ViewInspector):
         )
 
 
-class DefaultSchema(object):
+class DefaultSchema(ViewInspector):
     """Allows overriding AutoSchema using DEFAULT_SCHEMA_CLASS setting"""
     def __get__(self, instance, owner):
+        result = super(DefaultSchema, self).__get__(instance, owner)
+        if not isinstance(result, DefaultSchema):
+            return result
+
         inspector_class = api_settings.DEFAULT_SCHEMA_CLASS
         assert issubclass(inspector_class, ViewInspector), "DEFAULT_SCHEMA_CLASS must be set to a ViewInspector (usually an AutoSchema) subclass"
         inspector = inspector_class()

tests/test_schemas.py

@@ -105,6 +105,10 @@ class ExampleViewSet(ModelViewSet):
         """Deletion description."""
         raise NotImplementedError
 
+    @action(detail=False, schema=None)
+    def excluded_action(self, request):
+        pass
+
     def get_serializer(self, *args, **kwargs):
         assert self.request
         assert self.action
@@ -735,6 +739,45 @@ class TestAutoSchema(TestCase):
         assert len(fields) == 2
         assert "my_extra_field" in [f.name for f in fields]
 
+    @pytest.mark.skipif(not coreapi, reason='coreapi is not installed')
+    def test_viewset_action_with_schema(self):
+        class CustomViewSet(GenericViewSet):
+            @action(detail=True, schema=AutoSchema(manual_fields=[
+                coreapi.Field(
+                    "my_extra_field",
+                    required=True,
+                    location="path",
+                    schema=coreschema.String()
+                ),
+            ]))
+            def extra_action(self, pk, **kwargs):
+                pass
+
+        router = SimpleRouter()
+        router.register(r'detail', CustomViewSet, base_name='detail')
+
+        generator = SchemaGenerator()
+        view = generator.create_view(router.urls[0].callback, 'GET')
+        link = view.schema.get_link('/a/url/{id}/', 'GET', '')
+        fields = link.fields
+
+        assert len(fields) == 2
+        assert "my_extra_field" in [f.name for f in fields]
+
+    @pytest.mark.skipif(not coreapi, reason='coreapi is not installed')
+    def test_viewset_action_with_null_schema(self):
+        class CustomViewSet(GenericViewSet):
+            @action(detail=True, schema=None)
+            def extra_action(self, pk, **kwargs):
+                pass
+
+        router = SimpleRouter()
+        router.register(r'detail', CustomViewSet, base_name='detail')
+
+        generator = SchemaGenerator()
+        view = generator.create_view(router.urls[0].callback, 'GET')
+        assert view.schema is None
+
     @pytest.mark.skipif(not coreapi, reason='coreapi is not installed')
     def test_view_with_manual_schema(self):