fix: allow returning none for generic bindings

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

@@ -28,12 +28,17 @@ 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
 
     @classmethod
     def decode(cls, data: datumdef.Datum, *, trigger_metadata) -> typing.Any:
+        # Enabling support for Dapr bindings
+        # https://github.com/Azure/azure-functions-python-worker/issues/1316
+        if data is None:
+            return None
         data_type = data.type
 
         if data_type == 'string':
@@ -42,6 +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/endtoend/generic_functions/generic_functions_stein/function_app.py

@@ -1,6 +1,7 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License.
 import azure.functions as func
+import logging
 
 app = func.FunctionApp(http_auth_level=func.AuthLevel.ANONYMOUS)
 
@@ -29,3 +30,16 @@ def return_processed_last(req: func.HttpRequest, testEntity):
     table_name="EventHubBatchTest")
 def return_not_processed_last(req: func.HttpRequest, testEntities):
     return func.HttpResponse(status_code=200)
+
+
+@app.function_name(name="mytimer")
+@app.schedule(schedule="*/1 * * * * *", arg_name="mytimer",
+              run_on_startup=False,
+              use_monitor=False)
+@app.generic_input_binding(
+    arg_name="testEntity",
+    type="table",
+    connection="AzureWebJobsStorage",
+    table_name="EventHubBatchTest")
+def mytimer(mytimer: func.TimerRequest, testEntity) -> None:
+    logging.info("This timer trigger function executed successfully")

tests/endtoend/generic_functions/return_none/function.json

@@ -0,0 +1,21 @@
+{
+    "scriptFile": "main.py",
+    "bindings": [
+      {
+        "name": "mytimer",
+        "type": "timerTrigger",
+        "direction": "in",
+        "schedule": "*/1 * * * * *",
+        "runOnStartup": false
+      },
+      {
+        "direction": "in",
+        "type": "table",
+        "name": "testEntity",
+        "partitionKey": "test",
+        "rowKey": "WillBePopulatedWithGuid",
+        "tableName": "BindingTestTable",
+        "connection": "AzureWebJobsStorage"
+      }
+    ]
+  }

tests/endtoend/generic_functions/return_none/main.py

@@ -0,0 +1,10 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+import logging
+
+import azure.functions as func
+
+
+def main(mytimer: func.TimerRequest, testEntity) -> None:
+    logging.info("This timer trigger function executed successfully")

tests/endtoend/test_generic_functions.py

@@ -2,6 +2,9 @@
 # Licensed under the MIT License.
 from unittest import skipIf
 
+import time
+import typing
+
 from azure_functions_worker.utils.common import is_envvar_true
 from tests.utils import testutils
 from tests.utils.constants import DEDICATED_DOCKER_TEST, CONSUMPTION_DOCKER_TEST
@@ -41,6 +44,17 @@ def test_return_not_processed_last(self):
         r = self.webhost.request('GET', 'return_not_processed_last')
         self.assertEqual(r.status_code, 200)
 
+    def test_return_none(self):
+        time.sleep(1)
+        # Checking webhost status.
+        r = self.webhost.request('GET', '', no_prefix=True,
+                                 timeout=5)
+        self.assertTrue(r.ok)
+
+    def check_log_timer(self, host_out: typing.List[str]):
+        self.assertEqual(host_out.count("This timer trigger function executed "
+                                        "successfully"), 1)
+
 
 @skipIf(is_envvar_true(DEDICATED_DOCKER_TEST)
         or is_envvar_true(CONSUMPTION_DOCKER_TEST),

tests/unittests/generic_functions/foobar_nil_data/function.json

@@ -0,0 +1,10 @@
+{
+    "scriptFile": "main.py",
+    "bindings": [
+      {
+        "type": "generic",
+        "name": "input",
+        "direction": "in"
+      }
+    ]
+  }

tests/unittests/generic_functions/foobar_nil_data/main.py

@@ -0,0 +1,7 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+import logging
+
+
+def main(input) -> None:
+    logging.info("Hello World")

tests/unittests/test_mock_generic_functions.py

@@ -144,6 +144,8 @@ async def test_mock_generic_should_support_implicit_output(self):
             # implicitly
             self.assertEqual(r.response.result.status,
                              protos.StatusResult.Success)
+            self.assertEqual(r.response.return_value,
+                             protos.TypedData(bytes=b'\x00\x01'))
 
     async def test_mock_generic_should_support_without_datatype(self):
         async with testutils.start_mockhost(
@@ -195,3 +197,28 @@ async def test_mock_generic_implicit_output_exemption(self):
             # For the Durable Functions durableClient case
             self.assertEqual(r.response.result.status,
                              protos.StatusResult.Failure)
+
+    async def test_mock_generic_as_nil_data(self):
+        async with testutils.start_mockhost(
+                script_root=self.generic_funcs_dir) as host:
+
+            await host.init_worker("4.17.1")
+            func_id, r = await host.load_function('foobar_nil_data')
+
+            self.assertEqual(r.response.function_id, func_id)
+            self.assertEqual(r.response.result.status,
+                             protos.StatusResult.Success)
+
+            _, r = await host.invoke_function(
+                'foobar_nil_data', [
+                    protos.ParameterBinding(
+                        name='input',
+                        data=protos.TypedData()
+                    )
+                ]
+            )
+            self.assertEqual(r.response.result.status,
+                             protos.StatusResult.Success)
+            self.assertEqual(
+                r.response.return_value,
+                protos.TypedData())