Serialize activity output to JSON

Author: AnatoliB

samples-v2/openai_agents/function_app.py

@@ -50,12 +50,15 @@ def basic_hello_world_orchestrator(context):
 
 @app.activity_trigger(input_name="input")
 async def invoke_model_activity(input: str):
-    # Instantiate ModelActivity
     from _invoke_model_activity import ModelActivity, ActivityModelInput
+    from pydantic_core import to_json
 
     # Deserialize input string into ActivityModelInput object
     activity_input = ActivityModelInput.from_json(input)
 
     model_activity = ModelActivity()
-    return await model_activity.invoke_model_activity(activity_input)
+    result = await model_activity.invoke_model_activity(activity_input)
+
+    result_json = to_json(result).decode('utf-8')
+    return result_json