Hi all,
You're probably familiar with the mw.Api JavaScript class
<https://doc.wikimedia.org/mediawiki-core/master/js/mw.Api.html>
provided by MediaWiki, which can be used to make requests to our action API.
promise = ( new mw.Api() ).get( /*...*/ );
You may also know that the promises it returns are enhanced with an
.abort() method, which cancels the underlying HTTP request and rejects
the promise.
promise.abort();
The problem is that this method is only available on the original
promise object. If you try to chain promises, it no longer works:
promise.then( /*...*/ ).abort(); // Error: abort is not a function
Copying this method to the chained promise is very cumbersome. I will
spare you an example, but you can find it in the Phabricator task I
filed for this problem: T346984
<https://phabricator.wikimedia.org/T346984>. It's also not possible to
do if you use async/await, which we'll hopefully be able to use in
MediaWiki code soon.
The designers of the HTML5 Fetch API
<https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API> came up
with a different solution to the problem of cancelling HTTP requests:
abort signals
<https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#canceling_a_request>.
The Fetch API is increasingly being used outside of the MediaWiki world,
and so I would like to enhance our mw.Api to support the same approach.
*Here's my proposal:
https://gerrit.wikimedia.org/r/c/mediawiki/core/+/959350*
As you can tell by the six-digit patch number, I've had a hard time
finding anyone else interested in this, so I'm sending out this call for
reviewers. I hope there's someone out there with review rights who likes
the idea as well :)
You can read the documentation with examples of the new style here:
https://patchdemo.wmcloud.org/wikis/ee373520a4/w/docs/js/mw.Api-AbortController.html
The.abort() method is not being removed, and as a bonus, the patch
includes improved documentation for that style of cancellable promises:
https://patchdemo.wmcloud.org/wikis/ee373520a4/w/docs/js/mw.Api-AbortablePromise.html
--
Bartosz Dziewoński
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