CODEWITHSUNDEEP
pythongoogle-cloud-pubsub
Jasar Orion
Jasar Orion

Reputation: 686

How to handle errors or try again on publish to pubsub messages google with python

Im sending messages to a topic in pubsub with this script:

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path("my-project", "my-topic")

while True:
    msg = b"some message"
    future = publisher.publish(topic_path, msg)

    try:
        result = future.result()
    except Exception as ex:
        # handle exception
        print(ex)

    time.sleep(3)

My problem is how to make my print(ex) to print when a message is not posted on pubsub or detect when message wasn't sent and try to post it again.

Upvotes: 0

Views: 2310

Answers (1)

Ricco D
Ricco D

Reputation: 7277

You can check this article as it implemented error handling for publishing. A method was created for getting callbacks. It accepts future object and data string. If there is an exception, it will call exception() to return the raised exception.

def get_callback(f, data):
    def callback(f):
        try:
            print(f.result())
            futures.pop(data)
        except:  # noqa
            print("Please handle {} for {}.".format(f.exception(), data))

    return callback

This method was used to implement get_callback by passing the "future" and "data" parameters. Wherein future is a object and data is string.

for i in range(10):
    data = str(i)
    futures.update({data: None})
    # When you publish a message, the client returns a future.
    future = publisher.publish(topic_path, data.encode("utf-8"))
    futures[data] = future
    # Publish failures shall be handled in the callback function.
    future.add_done_callback(get_callback(future, data))
# Wait for all the publish futures to resolve before exiting.
while futures:
    time.sleep(5)

Upvotes: 1

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