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fix(step): use 'is not None' guard to preserve falsy return values in @step decorator #2940

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fix(step): use 'is not None' guard to preserve falsy return values in @step decorator #2940

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fix(step): use 'is not None' guard in @step decorator output capture
devteamaegis May 29, 2026
98d81cb
fix(message): rename classmethod parameter 'self' to 'cls' in Message…
devteamaegis May 29, 2026
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2 changes: 1 addition & 1 deletion backend/chainlit/message.py
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Original file line number Diff line number Diff line change
Expand Up @@ -59,7 +59,7 @@ def __post_init__(self) -> None:
self.id = str(uuid.uuid4())

@classmethod
def from_dict(self, _dict: StepDict):
def from_dict(cls, _dict: StepDict):
type = _dict.get("type", "assistant_message")
return Message(
id=_dict["id"],
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4 changes: 2 additions & 2 deletions backend/chainlit/step.py
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Original file line number Diff line number Diff line change
Expand Up @@ -123,7 +123,7 @@ async def async_wrapper(*args, **kwargs):
logger.exception(e)
result = await func(*args, **kwargs)
try:
if result and not step.output:
if result is not None and not step.output:

@sviat-barbutsa sviat-barbutsa Jun 16, 2026

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Nice fix. I think it would be worth adding a small regression test for the exact falsy return case this changes.

The existing step decorator tests cover normal truthy returns, but this PR changes both the async and sync wrappers to preserve falsy non-None values. A test with @step functions returning something like 0 or False would lock in the difference between “no return value” and “a real falsy return value”.

It'd be good to add some coverage for both async and sync decorated functions, and assert that the updated step output captures those values.

step.output = result
except Exception as e:
step.is_error = True
Expand Down Expand Up @@ -154,7 +154,7 @@ def sync_wrapper(*args, **kwargs):
logger.exception(e)
result = func(*args, **kwargs)
try:
if result and not step.output:
if result is not None and not step.output:
step.output = result
except Exception as e:
step.is_error = True
Expand Down