Annotate formatter and deserializer types

pyproject.toml

@@ -16,6 +16,7 @@ python = "^3.7"
 tornado = "^4 || ^5 || ^6"
 openapi-core = "^0.13.4"
 ietfparse = "^1.7.0"
+typing-extensions = "^3.7.4"
 
 [tool.poetry.dev-dependencies]
 black = { version = "*", allow-prereleases = true }

tornado_openapi3/handler.py

@@ -1,5 +1,6 @@
 import asyncio
 import logging
+import typing
 
 from openapi_core import create_spec  # type: ignore
 from openapi_core.casting.schemas.exceptions import CastError  # type: ignore
@@ -24,6 +25,7 @@ from openapi_core.validation.exceptions import InvalidSecurity  # type: ignore
 import tornado.web  # type: ignore
 
 from tornado_openapi3.requests import RequestValidator
+from tornado_openapi3.types import Deserializer, Formatter
 
 logger = logging.getLogger(__name__)
 
@@ -62,7 +64,7 @@ class OpenAPIRequestHandler(tornado.web.RequestHandler):
         return create_spec(self.spec_dict, validate_spec=False)
 
     @property
-    def custom_formatters(self) -> dict:
+    def custom_formatters(self) -> typing.Mapping[str, Formatter]:
         """A dictionary mapping value formats to formatter objects.
 
         A formatter object must provide:
@@ -73,7 +75,7 @@ class OpenAPIRequestHandler(tornado.web.RequestHandler):
         return dict()
 
     @property
-    def custom_media_type_deserializers(self) -> dict:
+    def custom_media_type_deserializers(self) -> typing.Mapping[str, Deserializer]:
         """A dictionary mapping media types to deserializing functions.
 
         If your endpoints make use of content types beyond ``application/json``,

tornado_openapi3/types.py

@@ -0,0 +1,14 @@
+import typing
+import typing_extensions
+
+Deserializer = typing.Callable[[typing.Union[bytes, str]], typing.Any]
+
+
+class Formatter(typing_extensions.Protocol):
+    """A type representing an OpenAPI formatter."""
+
+    def validate(self, value: str) -> bool:  # pragma: no cover
+        ...
+
+    def unmarshal(self, value: str) -> typing.Any:  # pragma: no cover
+        ...