Cornflower

Library for writing RabbitMQ message handlers with pydantic validation.

Installation

$ pip install cornflower

Example use:

Handler callback can accept zero or one argument of pydantic.BaseModel type. Message body will be validated automatically against specified schema.

from cornflower import MessageQueue, OutputMessage, MessageDeliveryMode
from pydantic import BaseModel


class UserMessage(BaseModel):
    username: str
    message: str


queue = MessageQueue(url="amqp://user:password@host:port")


@queue.listen(routing_key="user.registered")
def handle_user_register(message: UserMessage) -> None:
    # do something with validated message
    ...


@queue.listen(routing_key="user.login")
def handle_user_login() -> None:
    # callback with no arguments, handle message without
    # validating its body
    
    # sending message
    user_message = UserMessage(username="example", message="this is example")
    
    queue.dispatch(
        message=OutputMessage(
            body=user_message.dict(),
            routing_key="user.logout",
            delivery_mode=MessageDeliveryMode.PERSISTENT,
        )
    )


if __name__ == "__main__":
    queue.run()

Optional configuration

from cornflower import MessageQueue
from cornflower.options import QueueOptions, TransportOptions, ConsumerOptions

queue = MessageQueue(
    queue_options=QueueOptions(
        durable=True,
        exclusive=False,
        auto_delete=False,
    ),
    consumer_options=ConsumerOptions(
        prefetch_count=10
    ),
    transport_options=TransportOptions(
        confirm_publish=True,
    )
)