mandatory message

[Mani Amoozadeh]

I am using the simple python code to test mandatory messages. However, for some reasons the 'on_message_returned' does not work. What is wrong here?

import pika

import time

# Setup connection to RabbitMQ server

connection_param = pika.ConnectionParameters('localhost')

connection = pika.BlockingConnection(connection_param)

channel = connection.channel()

# Declare an exchange (direct type in this case)

exchange_name = 'example_exchange'

channel.exchange_declare(exchange=exchange_name, exchange_type='direct')

# Define a callback for returned messages

def on_message_returned(channel, method, properties, body):

print(f"Message returned: {body}")

channel.add_on_return_callback(on_message_returned)

for idx in range(100):

message = f"Mandatory Message {idx}"

channel.basic_publish(

exchange=exchange_name,

routing_key='non_existent_queue', # Routing key that matches no queue

body=message,

mandatory=True

)

print(f"Sent message: {message}")

time.sleep(5)

# Close the connection

connection.close()

[Luke Bakken]

Hello,

Your code has a couple issues. The best way for me to assist you is for you to do the following:

* Create a git repository (on GitHub, GitLab, etc) and add your code.

* Let me know the repository's information, and I can fork it.

* I will open a pull request with changes.

Thanks,

Luke

[Mani Amoozadeh]

Please find the code i nhere:
github.com/ManiAm/test_api/blob/main/rabitmq/7.mandatory_msg_producer.py

[Luke Bakken]

https://github.com/lukebakken/pika-python-9BC2mYZdOq8

I have added  an updated version of your code, as well as output.txt from running it on my system. As you can see, on_message_returned is called as expected.

My guess is that the issue is with your use of time.sleep. Do NOT do that, because it blocks Pika's I/O loop. You must not block Pika, ever!

[Mani Amoozadeh]

Thanks!

Once I added "connection.process_data_events(1)", the code worked as expected.
Why do we have to explicitly call it?

Follow up question:
How did you get the 'output.txt' file?

[Luke Bakken]

https://www.google.com/search?q=site%3Apika.readthedocs.io%2Fen%2Fstable%2F+process_data_events

python .\mandatory_msg_producer.py > .\output.txt 2>&1