Subclass SchemaGenerator instead of defining a new one

While the SchemaGenerator provided by DRF-YASG is not API-compatible
with the one used by DRF, it does use a lot of the methods and even
generates a DRF one internally. Given that this required quite a
bit of extra code to be written to do the wrapping, it makes sense
to instead just subclass it and get those additional benefits.

This should make it eaiser to migrate from the CoreAPISchemaGenerator,
which is what is currently being used, to the DRF-provided
OpenAPISchemaGenerator for the internal serialization. That was not
done here because there is still a lot of work that needs to be done
in order to enable that.

Author: kevin-brown

docs/conf.py

@@ -189,6 +189,7 @@
     ('py:class', 'rest_framework.serializers.Serializer'),
     ('py:class', 'rest_framework.renderers.BaseRenderer'),
     ('py:class', 'rest_framework.parsers.BaseParser'),
+    ('py:class', 'rest_framework.schemas.coreapi.SchemaGenerator'),
     ('py:class', 'rest_framework.schemas.generators.EndpointEnumerator'),
     ('py:class', 'rest_framework.views.APIView'),
 

docs/openapi.rst

@@ -146,7 +146,7 @@ This section describes where information is sourced from when using the default
          The Django `FORCE_SCRIPT_NAME`_ setting can be used to override the `SCRIPT_NAME`_ or set it when it's
          missing from the environment.
 
-   #. the longest common path prefix of all the urls in your API - see :meth:`.determine_path_prefix`
+   #. the longest common path prefix of all the urls in your API
 
 * When using API versioning with ``NamespaceVersioning`` or ``URLPathVersioning``, versioned endpoints that do not
   match the version used to access the ``SchemaView`` will be excluded from the endpoint list - for example,

src/drf_yasg/generators.py

@@ -163,7 +163,7 @@ def unescape_path(self, path):
         return clean_path
 
 
-class OpenAPISchemaGenerator(object):
+class OpenAPISchemaGenerator(SchemaGenerator):
     """
     This class iterates over all registered API endpoints and returns an appropriate OpenAPI 2.0 compliant schema.
     Method implementations shamelessly stolen and adapted from rest-framework ``SchemaGenerator``.
@@ -188,7 +188,8 @@ def __init__(self, info, version='', url=None, patterns=None, urlconf=None):
         :param urlconf: if patterns is not given, use this urlconf to enumerate patterns;
             if not given, the default urlconf is used
         """
-        self._gen = SchemaGenerator(info.title, url, info.get('description', ''), patterns, urlconf)
+        super(OpenAPISchemaGenerator, self).__init__(info.title, url, info.get('description', ''), patterns, urlconf)
+
         self.info = info
         self.version = version
         self.consumes = []
@@ -204,10 +205,6 @@ def __init__(self, info, version='', url=None, patterns=None, urlconf=None):
             if parsed_url.path:
                 logger.warning("path component of api base URL %s is ignored; use FORCE_SCRIPT_NAME instead" % url)
 
-    @property
-    def url(self):
-        return self._gen.url
-
     def get_security_definitions(self):
         """Get the security schemes for this API. This determines what is usable in security requirements,
         and helps clients configure their authorization credentials.
@@ -278,7 +275,7 @@ def create_view(self, callback, method, request=None):
         :type request: rest_framework.request.Request or None
         :return: the view instance
         """
-        view = self._gen.create_view(callback, method, request)
+        view = super(OpenAPISchemaGenerator, self).create_view(callback, method, request)
         overrides = getattr(callback, '_swagger_auto_schema', None)
         if overrides is not None:
             # decorated function based view must have its decorator information passed on to the re-instantiated view
@@ -290,24 +287,6 @@ def create_view(self, callback, method, request=None):
         setattr(view, 'swagger_fake_view', True)
         return view
 
-    def coerce_path(self, path, view):
-        """Coerce {pk} path arguments into the name of the model field, where possible. This is cleaner for an
-        external representation (i.e. "this is an identifier", not "this is a database primary key").
-
-        :param str path: the path
-        :param rest_framework.views.APIView view: associated view
-        :rtype: str
-        """
-        if '{pk}' not in path:
-            return path
-
-        model = getattr(get_queryset_from_view(view), 'model', None)
-        if model:
-            field_name = get_pk_name(model)
-        else:
-            field_name = 'id'
-        return path.replace('{pk}', '{%s}' % field_name)
-
     def get_endpoints(self, request):
         """Iterate over all the registered endpoints in the API and return a fake view with the right parameters.
 
@@ -316,55 +295,18 @@ def get_endpoints(self, request):
         :return: {path: (view_class, list[(http_method, view_instance)])
         :rtype: dict[str,(type,list[(str,rest_framework.views.APIView)])]
         """
-        enumerator = self.endpoint_enumerator_class(self._gen.patterns, self._gen.urlconf, request=request)
+        enumerator = self.endpoint_enumerator_class(self.patterns, self.urlconf, request=request)
         endpoints = enumerator.get_api_endpoints()
 
         view_paths = defaultdict(list)
         view_cls = {}
         for path, method, callback in endpoints:
             view = self.create_view(callback, method, request)
-            path = self.coerce_path(path, view)
+            path = self.coerce_path(path, method, view)
             view_paths[path].append((method, view))
             view_cls[path] = callback.cls
         return {path: (view_cls[path], methods) for path, methods in view_paths.items()}
 
-    def get_operation_keys(self, subpath, method, view):
-        """Return a list of keys that should be used to group an operation within the specification. ::
-
-          /users/                   ("users", "list"), ("users", "create")
-          /users/{pk}/              ("users", "read"), ("users", "update"), ("users", "delete")
-          /users/enabled/           ("users", "enabled")  # custom viewset list action
-          /users/{pk}/star/         ("users", "star")     # custom viewset detail action
-          /users/{pk}/groups/       ("users", "groups", "list"), ("users", "groups", "create")
-          /users/{pk}/groups/{pk}/  ("users", "groups", "read"), ("users", "groups", "update")
-
-        :param str subpath: path to the operation with any common prefix/base path removed
-        :param str method: HTTP method
-        :param view: the view associated with the operation
-        :rtype: list[str]
-        """
-        return self._gen.get_keys(subpath, method, view)
-
-    def determine_path_prefix(self, paths):
-        """
-        Given a list of all paths, return the common prefix which should be
-        discounted when generating a schema structure.
-
-        This will be the longest common string that does not include that last
-        component of the URL, or the last component before a path parameter.
-
-        For example: ::
-
-            /api/v1/users/
-            /api/v1/users/{pk}/
-
-        The path prefix is ``/api/v1/``.
-
-        :param list[str] paths: list of paths
-        :rtype: str
-        """
-        return self._gen.determine_path_prefix(paths)
-
     def should_include_endpoint(self, path, method, view, public):
         """Check if a given endpoint should be included in the resulting schema.
 
@@ -375,7 +317,7 @@ def should_include_endpoint(self, path, method, view, public):
         :returns: true if the view should be excluded
         :rtype: bool
         """
-        return public or self._gen.has_view_permissions(path, method, view)
+        return public or self.has_view_permissions(path, method, view)
 
     def get_paths_object(self, paths):
         """Construct the Swagger Paths object.
@@ -436,7 +378,7 @@ def get_operation(self, view, path, prefix, method, components, request):
         :param Request request: the request made against the schema view; can be None
         :rtype: openapi.Operation
         """
-        operation_keys = self.get_operation_keys(path[len(prefix):], method, view)
+        operation_keys = self.get_keys(path[len(prefix):], method, view)
         overrides = self.get_overrides(view, method)
 
         # the inspector class can be specified, in decreasing order of priorty,