Skip to content

fix: Invoke callback handler for structured_output #857

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Sep 18, 2025
Merged

fix: Invoke callback handler for structured_output #857

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 5 additions & 2 deletions src/strands/agent/agent.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -514,8 +514,11 @@ async def structured_output_async(self, output_model: Type[T], prompt: AgentInpu
)
events = self.model.structured_output(output_model, temp_messages, system_prompt=self.system_prompt)
async for event in events:
if "callback" in event:
self.callback_handler(**cast(dict, event["callback"]))
if isinstance(event, TypedEvent):
event.prepare(invocation_state={})
if event.is_callback_event:
self.callback_handler(**event.as_dict())

structured_output_span.add_event(
"gen_ai.choice", attributes={"message": serialize(event["output"].model_dump())}
)
Expand Down
131 changes: 131 additions & 0 deletions tests/strands/agent/hooks/test_agent_events.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,10 +3,12 @@
from unittest.mock import ANY, MagicMock, call

import pytest
from pydantic import BaseModel

import strands
from strands import Agent
from strands.agent import AgentResult
from strands.models import BedrockModel
from strands.types._events import TypedEvent
from strands.types.exceptions import ModelThrottledException
from tests.fixtures.mocked_model_provider import MockedModelProvider
Expand Down Expand Up @@ -440,3 +442,132 @@ async def test_event_loop_cycle_text_response_throttling_early_end(
# Ensure that all events coming out of the agent are *not* typed events
typed_events = [event for event in tru_events if isinstance(event, TypedEvent)]
assert typed_events == []


@pytest.mark.asyncio
async def test_structured_output(agenerator):
# we use bedrock here as it uses the tool implementation
model = BedrockModel()
model.stream = MagicMock()
model.stream.return_value = agenerator(
[
{
"contentBlockStart": {
"start": {"toolUse": {"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ", "name": "Person"}},
"contentBlockIndex": 0,
}
},
{"contentBlockDelta": {"delta": {"toolUse": {"input": ""}}, "contentBlockIndex": 0}},
{"contentBlockDelta": {"delta": {"toolUse": {"input": '{"na'}}, "contentBlockIndex": 0}},
{"contentBlockDelta": {"delta": {"toolUse": {"input": 'me"'}}, "contentBlockIndex": 0}},
{"contentBlockDelta": {"delta": {"toolUse": {"input": ': "J'}}, "contentBlockIndex": 0}},
{"contentBlockDelta": {"delta": {"toolUse": {"input": 'ohn"'}}, "contentBlockIndex": 0}},
{"contentBlockDelta": {"delta": {"toolUse": {"input": ', "age": 3'}}, "contentBlockIndex": 0}},
{"contentBlockDelta": {"delta": {"toolUse": {"input": "1}"}}, "contentBlockIndex": 0}},
{"contentBlockStop": {"contentBlockIndex": 0}},
{"messageStop": {"stopReason": "tool_use"}},
{
"metadata": {
"usage": {"inputTokens": 407, "outputTokens": 53, "totalTokens": 460},
"metrics": {"latencyMs": 1572},
}
},
]
)

mock_callback = unittest.mock.Mock()
agent = Agent(model=model, callback_handler=mock_callback)

class Person(BaseModel):
name: str
age: float

await agent.structured_output_async(Person, "John is 31")

exp_events = [
{
"event": {
"contentBlockStart": {
"start": {"toolUse": {"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ", "name": "Person"}},
"contentBlockIndex": 0,
}
}
},
{"event": {"contentBlockDelta": {"delta": {"toolUse": {"input": ""}}, "contentBlockIndex": 0}}},
{
"delta": {"toolUse": {"input": ""}},
"current_tool_use": {
"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ",
"name": "Person",
"input": {"name": "John", "age": 31},
},
},
{"event": {"contentBlockDelta": {"delta": {"toolUse": {"input": '{"na'}}, "contentBlockIndex": 0}}},
{
"delta": {"toolUse": {"input": '{"na'}},
"current_tool_use": {
"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ",
"name": "Person",
"input": {"name": "John", "age": 31},
},
},
{"event": {"contentBlockDelta": {"delta": {"toolUse": {"input": 'me"'}}, "contentBlockIndex": 0}}},
{
"delta": {"toolUse": {"input": 'me"'}},
"current_tool_use": {
"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ",
"name": "Person",
"input": {"name": "John", "age": 31},
},
},
{"event": {"contentBlockDelta": {"delta": {"toolUse": {"input": ': "J'}}, "contentBlockIndex": 0}}},
{
"delta": {"toolUse": {"input": ': "J'}},
"current_tool_use": {
"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ",
"name": "Person",
"input": {"name": "John", "age": 31},
},
},
{"event": {"contentBlockDelta": {"delta": {"toolUse": {"input": 'ohn"'}}, "contentBlockIndex": 0}}},
{
"delta": {"toolUse": {"input": 'ohn"'}},
"current_tool_use": {
"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ",
"name": "Person",
"input": {"name": "John", "age": 31},
},
},
{"event": {"contentBlockDelta": {"delta": {"toolUse": {"input": ', "age": 3'}}, "contentBlockIndex": 0}}},
{
"delta": {"toolUse": {"input": ', "age": 3'}},
"current_tool_use": {
"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ",
"name": "Person",
"input": {"name": "John", "age": 31},
},
},
{"event": {"contentBlockDelta": {"delta": {"toolUse": {"input": "1}"}}, "contentBlockIndex": 0}}},
{
"delta": {"toolUse": {"input": "1}"}},
"current_tool_use": {
"toolUseId": "tooluse_efwXnrK_S6qTyxzcq1IUMQ",
"name": "Person",
"input": {"name": "John", "age": 31},
},
},
{"event": {"contentBlockStop": {"contentBlockIndex": 0}}},
{"event": {"messageStop": {"stopReason": "tool_use"}}},
{
"event": {
"metadata": {
"usage": {"inputTokens": 407, "outputTokens": 53, "totalTokens": 460},
"metrics": {"latencyMs": 1572},
}
}
},
]

exp_calls = [call(**event) for event in exp_events]
act_calls = mock_callback.call_args_list
assert act_calls == exp_calls
Loading