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fix(pubsub): accept messages from requests without CloudEvent headers #334

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fix(pubsub): accept messages from requests without CloudEvent headers #334

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12 changes: 9 additions & 3 deletions src/firebase_functions/pubsub_fn.py
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Original file line number Diff line number Diff line change
Expand Up @@ -87,9 +87,9 @@ class MessagePublishedData(_typing.Generic[T]):
Google Cloud Pub/Sub message.
"""

subscription: str
subscription: str | None
"""
A subscription resource.
A subscription resource. ``None`` when the request had no CloudEvent headers.
"""


Expand All @@ -107,6 +107,12 @@ def _message_handler(
data = event_dict["data"]
message_dict = data["message"]

# When a request has no CloudEvent headers, functions-framework builds the
# message itself with camelCase keys only, an "@type" key and no subscription.
message_dict.setdefault("message_id", message_dict.get("messageId"))
message_dict.setdefault("publish_time", message_dict.get("publishTime"))
Comment on lines +112 to +113

@gemini-code-assist gemini-code-assist Bot Nov 5, 2026

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medium

Using message_dict.get() here will return None if the camelCase keys are missing. If both the snake_case and camelCase keys are absent (e.g., in a malformed request), setdefault will set the keys to None. This can lead to confusing downstream errors, such as a TypeError: argument of type 'NoneType' is not iterable when checking for . in publish_time on line 119, instead of a standard KeyError. Checking for the existence of the camelCase keys before calling setdefault avoids injecting None values.

Suggested change
message_dict.setdefault("message_id", message_dict.get("messageId"))
message_dict.setdefault("publish_time", message_dict.get("publishTime"))
if "messageId" in message_dict:
message_dict.setdefault("message_id", message_dict["messageId"])
if "publishTime" in message_dict:
message_dict.setdefault("publish_time", message_dict["publishTime"])

message_dict.pop("@type", None)

# if no microseconds are present, we should set them to 0 to prevent parsing from failing
if "." not in event_dict["time"]:
event_dict["time"] = event_dict["time"].replace("Z", ".000000Z")
Expand Down Expand Up @@ -147,7 +153,7 @@ def _message_handler(
**message_dict,
ordering_key=ordering_key,
),
subscription=data["subscription"],
subscription=data.get("subscription"),
)

event_dict["data"] = message
Expand Down
28 changes: 28 additions & 0 deletions tests/test_pubsub_fn.py
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,8 @@
from unittest.mock import MagicMock

from cloudevents.http import CloudEvent as _CloudEvent
from flask import Flask, request
from functions_framework import event_conversion

from firebase_functions import core
from firebase_functions.pubsub_fn import (
Expand Down Expand Up @@ -182,3 +184,29 @@ def test_publish_time_is_timezone_aware_datetime(self):
_dt.datetime(2023, 3, 11, 13, 25, 37, 403000, tzinfo=_dt.timezone.utc),
)
self.assertEqual(message.publish_time.utcoffset(), _dt.timedelta(0))

def test_push_body_without_cloudevent_headers_reaches_handler(self):
push_body = {
"message": {
"attributes": {"key": "value"},
"data": "eyJ0ZXN0IjogInZhbHVlIn0=",
"messageId": "message-id-123",
"publishTime": "2023-03-11T13:25:37.403Z",
},
"subscription": "projects/p/subscriptions/s",
}
with Flask(__name__).test_request_context("/", method="POST", json=push_body):
raw = event_conversion.background_event_to_cloud_event(request)

func = MagicMock()
_message_handler(func, raw)

data = func.call_args.args[0].data
self.assertEqual(data.message.message_id, "message-id-123")
self.assertEqual(
data.message.publish_time,
_dt.datetime(2023, 3, 11, 13, 25, 37, 403000, tzinfo=_dt.timezone.utc),
)
self.assertEqual(data.message.attributes, {"key": "value"})
self.assertEqual(data.message.json, {"test": "value"})
self.assertIsNone(data.subscription)
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