How to access Msg.Metadata (delivery attempts, timestamp, etc.) using FastStream's NatsMessage?

[Atanusaha143]

I'm currently using FastStream with the NATS backend (JetStream enabled) and trying to handle retries more intelligently based on delivery attempts.

NATS nats.py Msg.Metadata exposes very useful properties like:

• num_delivered
• timestamp
• sequence etc.

But when I receive a message in FastStream like:

@broker.subscriber("test_subject")
async def consumer(msg: NatsMessage):
    ...

I don't have access to .metadata if trying to access it throws:

AttributeError: 'NatsMessage' object has no attribute 'metadata'

💡 Question:

1. Is there currently a way to access these metadata properties (especially num_delivered) in a FastStream consumer? If it is then how can we do that?
2. If not, is there a recommended workaround for implementing retry logic that depends on the delivery count?

🔍 Notes:

• I’ve confirmed JetStream is enabled.
• The msg.body works fine for payloads.

[Lancetnik]

You can get access to raw nats-py message by NatsMessage.raw_message.[metadate/smth else]

[Atanusaha143]

@Lancetnik It seems _metadata is None even when the message is redelivered. Could you please let me know how to access these (num_delivered, timestamp) property?

[Lancetnik]

The following example works fine for me

from faststream import FastStream, Logger
from faststream.nats import NatsBroker, NatsMessage

broker = NatsBroker()
app = FastStream(broker)


@broker.subscriber("test", stream="metadata")
async def test_subscriber(msg: NatsMessage, logger: Logger) -> None:
    logger.info(msg.raw_message.metadata.num_delivered)


@app.after_startup
async def _() -> None:
    await broker.publish("Hi!", "test")