Adjust ManualSchema to take fields

… and `description`.

Allows `url` and `action` to remain dynamic

docs/api-guide/schemas.md

@@ -199,17 +199,28 @@ To customise the `Link` generation you may:
 
     This provides complete control over view introspection.
 
-* Instantiate `ManualSchema` on your view, providing the Core API `Link`
-  explicitly:
+* Instantiate `ManualSchema` on your view, providing the Core API `Fields` for
+  the view explicitly:
 
         from rest_framework.views import APIView
         from rest_framework.schemas import ManualSchema
 
         class CustomView(APIView):
             ...
-            schema = ManualSchema(
-                coreapi.Link(...)
-            )
+            schema = ManualSchema(fields=[
+                coreapi.Field(
+                    "first_field",
+                    required=True,
+                    location="path",
+                    schema=coreschema.String()
+                ),
+                coreapi.Field(
+                    "second_field",
+                    required=True,
+                    location="path",
+                    schema=coreschema.String()
+                ),
+            ])
 
     This allows manually specifying the schema for some views whilst maintaining
     automatic generation elsewhere.
@@ -580,17 +591,31 @@ Return a list of `coreapi.Link()` instances, as returned by the `get_schema_fiel
 
 ## ManualSchema
 
-Allows specifying a manual schema for a view:
+Allows manually providing a list of `coreapi.Field` instances for the schema,
+plus an optional description.
 
     class MyView(APIView):
-      schema = ManualSchema(coreapi.Link(
-        url='/example/',
-        action='get',
-        fields=[]
-      ))
+      schema = ManualSchema(fields=[
+            coreapi.Field(
+                "first_field",
+                required=True,
+                location="path",
+                schema=coreschema.String()
+            ),
+            coreapi.Field(
+                "second_field",
+                required=True,
+                location="path",
+                schema=coreschema.String()
+            ),
+        ]
+      )
 
-The `ManualSchema` constructor takes a single parameter `link`,
-the `coreapi.Link` instance for the view.
+The `ManualSchema` constructor takes two arguments:
+
+**`fields`**: A list of `coreapi.Field` instances. Required.
+
+**`description`**: A string description. Optional.
 
 ---
 

rest_framework/schemas/inspectors.py

@@ -364,11 +364,31 @@ class AutoSchema(ViewInspector):
 
 class ManualSchema(ViewInspector):
     """
-    Overrides get_link to return manually specified schema.
+    Allows providing a list of coreapi.Fields,
+    plus an optional description.
     """
-    def __init__(self, link):
-        assert isinstance(link, coreapi.Link)
-        self._link = link
+    def __init__(self, fields, description=''):
+        """
+        Parameters:
+
+        * `fields`: list of `coreapi.Field` instances.
+        * `descripton`: String description for view. Optional.
+        """
+        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
+
+    def get_link(self, path, method, base_url):
+
+        if base_url and path.startswith('/'):
+            path = path[1:]
+
+        return coreapi.Link(
+            url=urlparse.urljoin(base_url, path),
+            action=method.lower(),
+            encoding=None,
+            fields=self._fields,
+            description=self._description
+        )
 
-    def get_link(self, *args):
         return self._link

tests/test_schemas.py

@@ -534,15 +534,46 @@ class TestDescriptor(TestCase):
 
     def test_view_with_manual_schema(self):
 
-        expected = coreapi.Link(
-            url='/example/',
-            action='get',
-            fields=[]
-        )
+        path = '/example'
+        method = 'get'
+        base_url = None
+
+        fields = [
+            coreapi.Field(
+                "first_field",
+                required=True,
+                location="path",
+                schema=coreschema.String()
+            ),
+            coreapi.Field(
+                "second_field",
+                required=True,
+                location="path",
+                schema=coreschema.String()
+            ),
+            coreapi.Field(
+                "third_field",
+                required=True,
+                location="path",
+                schema=coreschema.String()
+            ),
+        ]
+        description = "A test endpoint"
 
         class CustomView(APIView):
-            schema = ManualSchema(expected)
+            """
+            ManualSchema takes list of fields for endpoint.
+            - Provides url and action, which are always dynamic
+            """
+            schema = ManualSchema(fields, description)
+
+        expected = coreapi.Link(
+            url=path,
+            action=method,
+            fields=fields,
+            description=description
+        )
 
         view = CustomView()
-        link = view.schema.get_link()
+        link = view.schema.get_link(path, method, base_url)
         assert link == expected