[Queue] QueueClient.receive_messages() doesn't react to `messages_per_page` parameter

[evelyn-ys]

• Package Name: azure-storage-queue
• Python Version: Python 3.7

Describe the bug
When calling the function "receive_messages()", all messages will return no matter what value I set messages_per_page

[annatisch]

Thanks @evelyn-ys,
You are correct in that, by default the iterator will iterate through all the messages.
The "paging" mechanism is not exposed here, however you should be able to access a specific page size with logic like this:

page_size = 5
for page_of_messages in client.receive_messages(messages_per_page=page_size).by_page():
    assert len(page_of_messages) <= 5
    for message in page_of_messages:
        print(message

Let me know if the above snippet is still not correctly handling the messages_per_page value :)

[evelyn-ys]

So the logic behind client.receive_messages(messages_per_page=page_size).by_page() is that we dequeue all messages and split the response to pages? For example, I have 15 messages in my queue, and the client.receive_messages(messages_per_page=5).by_page() will get 15 messages in 3 pages? what if I only want to dequeue 5 messages?

[annatisch]

Hi @evelyn-ys - The iterator does not dequeue all the messages before splitting into pages - instead, they are retrieved in batches, or "pages" at a time.
So if you only wish to dequeue the first 5 messages - you would not loop the iterator to completion.
For example, you could call next() like this to pull only one page at a time:

page_size = 5
page_iter = client.receive_messages(messages_per_page=page_size).by_page()

single_page = next(page_iter)
assert len(single_page) <= 5
for message in single_page:
    print(message)

[evelyn-ys]

Hi @evelyn-ys - The iterator does not dequeue all the messages before splitting into pages - instead, they are retrieved in batches, or "pages" at a time.
So if you only wish to dequeue the first 5 messages - you would not loop the iterator to completion.
For example, you could call next() like this to pull only one page at a time:

page_size = 5
page_iter = client.receive_messages(messages_per_page=page_size).by_page()

single_page = next(page_iter)
assert len(single_page) <= 5
for message in single_page:
    print(message)

Thanks a lot!

[tasherif-msft]

Hi @evelyn-ys , just wanted to inform you that I have just created a PR that makes it much simpler to pop one message from the queue. Here's the PR: #14855
This will give you the ability to retrieve one message at a time without lots of code overhead to do so :)