Fix async generator handling

connexion/decorators/response.py

@@ -186,10 +186,12 @@ def __call__(self, function: t.Callable) -> t.Callable:
         async def wrapper(*args, **kwargs):
             """
             This method converts a handler response to a framework response.
-            The handler response can be a ConnexionResponse, a framework response, a tuple or an
-            object.
+            The handler response can be a ConnexionResponse, a framework response, a tuple, an
+            object or a coroutine.
             """
             handler_response = await function(*args, **kwargs)
+            if isinstance(handler_response, t.Coroutine):
+                handler_response = await handler_response
             if self.framework.is_framework_response(handler_response):
                 return handler_response
             elif isinstance(handler_response, ConnexionResponse):

connexion/frameworks/starlette.py

@@ -5,6 +5,7 @@
 import starlette.convertors
 from starlette.responses import JSONResponse as StarletteJSONResponse
 from starlette.responses import Response as StarletteResponse
+from starlette.responses import StreamingResponse as StarletteStreamingResponse
 from starlette.types import Receive, Scope
 
 from connexion.frameworks.abstract import Framework
@@ -37,6 +38,8 @@ def build_response(
     ):
         if isinstance(data, dict) or isinstance(data, list):
             response_cls = StarletteJSONResponse
+        elif isinstance(data, t.Generator) or isinstance(data, t.AsyncGenerator):
+            response_cls = StarletteStreamingResponse
         else:
             response_cls = StarletteResponse