fix serialization of custom output classes in TaskOrchestrationExecutor

azure/durable_functions/decorators/durable_app.py

@@ -1,6 +1,6 @@
 #  Copyright (c) Microsoft Corporation. All rights reserved.
 #  Licensed under the MIT License.
-from .metadata import OrchestrationTrigger, ActivityTrigger, EntityTrigger,\
+from .metadata import OrchestrationTrigger, ActivityTrigger, EntityTrigger, \
     DurableClient
 from typing import Callable, Optional
 from azure.durable_functions.entity import Entity

azure/durable_functions/models/TaskOrchestrationExecutor.py

@@ -9,7 +9,7 @@
 from collections import namedtuple
 import json
 from ..models.entities.ResponseMessage import ResponseMessage
-from azure.functions._durable_functions import _deserialize_custom_object
+from azure.functions._durable_functions import _deserialize_custom_object, _serialize_custom_object
 
 
 class TaskOrchestrationExecutor:
@@ -276,12 +276,12 @@ def get_orchestrator_state_str(self) -> str:
             message contains in it the string representation of the orchestration's
             state
         """
-        if(self.output is not None):
+        if (self.output is not None):
             try:
                 # Attempt to serialize the output. If serialization fails, raise an
                 # error indicating that the orchestration output is not serializable,
                 # which is not permitted in durable Python functions.
-                json.dumps(self.output)
+                json.dumps(self.output, default=_serialize_custom_object)
             except Exception as e:
                 self.output = None
                 self.exception = e

tests/orchestrator/orchestrator_test_utils.py

@@ -1,5 +1,7 @@
 import json
 from typing import Callable, Iterator, Any, Dict, List
+
+from azure.functions._durable_functions import _deserialize_custom_object
 from jsonschema import validate
 
 from azure.durable_functions.models import DurableOrchestrationContext, DurableEntityContext
@@ -71,7 +73,7 @@ def get_orchestration_state_result(
         orchestrator = Orchestrator(user_code)
         result_of_handle = orchestrator.handle(
             DurableOrchestrationContext.from_json(context_as_string))
-    result = json.loads(result_of_handle)
+    result = json.loads(result_of_handle, object_hook=_deserialize_custom_object)
     return result
 
 def get_entity_state_result(

tests/orchestrator/test_serialization.py

@@ -1,3 +1,5 @@
+from dataclasses import dataclass
+
 from azure.durable_functions.models.ReplaySchema import ReplaySchema
 from tests.test_utils.ContextBuilder import ContextBuilder
 from .orchestrator_test_utils \
@@ -28,4 +30,40 @@ def test_serialization_of_False():
     expected["output"] = False
 
     assert_valid_schema(result)
-    assert_orchestration_state_equals(expected, result)
+    assert_orchestration_state_equals(expected, result)
+
+
+@dataclass
+class CustomResult():
+  message: str
+
+  def to_json(self):
+      return {"message": self.message}
+
+  @classmethod
+  def from_json(cls, data):
+      return cls(message=data["message"])
+
+def generator_function_with_custom_class(context):
+    return CustomResult(message="Custom serialization test")
+
+def test_serialization_of_custom_class():
+    """Test that an orchestrator can return False."""
+
+    context_builder = ContextBuilder("serialize custom class")
+
+    result = get_orchestration_state_result(
+        context_builder, generator_function_with_custom_class)
+
+    expected_output = CustomResult(message="Custom serialization test")
+    expected_state = base_expected_state(output=expected_output)
+
+    expected_state._is_done = True
+    expected = expected_state.to_json()
+
+    # Since we're essentially testing the `to_json` functionality,
+    # we explicitely ensure that the output is set
+    expected["output"] = expected_output
+
+    assert_valid_schema(result)
+    assert_orchestration_state_equals(expected, result)