SchemaGenerator doesn't work with mounted apps that don't implement routes

[and3rson]

Related issue: mirumee/ariadne#975

Since ariadne doesn't expose any routes but a single __call__ method, starlette's SchemaGenerator.get_endpoints doesn't return any routes for it.

Is it possible to make SchemaGenerator call some method (if it exists) on a mounted app (say, get_openapi_schema() -> str or get_openapi_endpoints() -> Iterable[EndpointInfo]) in order to allow the latter to provide openapi spec for starlette? Alternative option could be to take __doc__ directly from the mounted app in addition to taking its .routes. Not sure if either of these approaches will allow the mounted app to provide spec for more than one endpoint though...

Any suggestions are welcome!

[rafalp]

Support for extra argument on Mount() that would be a list of dicts with schema contents would be more explicit and leave it to ASGI apps to provide a way to retrieve schema's data by developer integrating those into their project, eg:

graphql = GraphQL(...)

routes = [
  Mount("/graphql", app=graphql, name="graphql", schema=graphql.get_openapi_schema())
]

For schema we could do:

class RouteResponseSchema(TypedDict):
    description: str | null
    examples: str | null
    

class RouteSchema(TypedDict):
    path: str
    method: str
    description: str | null
    responses: Dict[int, RouteResponseSchema] | null


Schema = Sequence[RouteSchema]