added back support for returning None

Author: hallvictoria

azure_functions_worker/bindings/datumdef.py

@@ -197,6 +197,8 @@ def datum_as_proto(datum: Datum) -> protos.TypedData:
             enable_content_negotiation=False,
             body=datum_as_proto(datum.value['body']),
         ))
+    elif datum.type is None:
+        return None
     else:
         raise NotImplementedError(
             'unexpected Datum type: {!r}'.format(datum.type)

azure_functions_worker/bindings/generic.py

@@ -28,6 +28,8 @@ def encode(cls, obj: Any, *,
 
         elif isinstance(obj, (bytes, bytearray)):
             return datumdef.Datum(type='bytes', value=bytes(obj))
+        elif obj is None:
+            return datumdef.Datum(type=None, value=obj)
         else:
             raise NotImplementedError
 
@@ -45,6 +47,8 @@ def decode(cls, data: datumdef.Datum, *, trigger_metadata) -> typing.Any:
             result = data.value
         elif data_type == 'json':
             result = data.value
+        elif data_type is None:
+            result = None
         else:
             raise ValueError(
                 f'unexpected type of data received for the "generic" binding '

azure_functions_worker/bindings/meta.py

@@ -178,9 +178,8 @@ def to_outgoing_param_binding(binding: str, obj: typing.Any, *,
             rpc_shared_memory=shared_mem_value)
     else:
         # If not, send it as part of the response message over RPC
+        # rpc_val can be None here as we now support a None return type
         rpc_val = datumdef.datum_as_proto(datum)
-        if rpc_val is None:
-            raise TypeError('Cannot convert datum to rpc_val')
         return protos.ParameterBinding(
             name=out_name,
             data=rpc_val)

tests/unittests/generic_functions/foobar_nil_data/main.py

@@ -3,7 +3,5 @@
 import logging
 
 
-def main(input):
+def main(input) -> None:
     logging.info("Hello World")
-    # The function must return a non-None value
-    return "This is fine"

tests/unittests/test_mock_generic_functions.py

@@ -222,4 +222,4 @@ async def test_mock_generic_as_nil_data(self):
                              protos.StatusResult.Success)
             self.assertEqual(
                 r.response.return_value,
-                protos.TypedData(string="This is fine"))
+                protos.TypedData())