Support for CancellationToken's

[clairernovotny]

If an interface method that supplies a CancellationToken, Refit should pass it to the underlying HttpClient call

[anaisbetts]

Right now, cancellation is supported via the IObservable interface (i.e. unsubscribing early from Observable == cancel the call). I'm not suuuuuuper excited to try to cram it in as a magic parameter

[clairernovotny]

WebAPI/MVC already does the magic parameter convention. If your web api method has a CancellationToken, it'll be populated so if the request dies, you can propagate it.

For people using the Task method, we need a way to abort it...

[mburbea]

👍 On this. I currently workaround this by spawning a separate http client for each request, and binding the client's CancelPendingRequest method to the cancellationToken. It's ugly and inefficient, it'd be much nicer to just cancel the request I care about instead of all of them.

[MKuckert]

Seems like this feature is implemented, right? I simply add a parameter of type CancellationToken to my method, or am I wrong?

[clairernovotny]

Should be, yes.

[anaisbetts]

We did it!

[michelmoorlag]

I am a bit lost here. I am using Refit 2.4.1 in a Xamarin Forms project and I would like to be able to cancel http requests with a CancellationToken. So If I understand it correct I can add a CancellationToken parameter to the methods in the interface and then pass it in the implementation.

1. Is my assumption correct?
2. Is the location of the parameter important like first, last or?
3. Does version 2.4.1 has this functionality, if not what version does?
4. I am using a customHandler with a overridden SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) method. Will this cancellationToken be the one that is passed in the implementation?

A small example would be highly appreciated.

[michelmoorlag]

I just implemented it and based on that I can conclude the following:

1. Yes
2. Don't know, I have always put the token as first parameter and that seems to work
3. Yes
4. Yes
   Maybe somebody who knows more how refit works can confirm this?

[bennor]

Yes to all. Doesn't matter what the order of parameters is on your interface (they just get read out as a collection).

[michelmoorlag]

Thank you Bennor.
My app kicks off some requests in the background and in some situation like logout it is really handy to be able to cancel these requests with a cancellationtoken. This now works really well but documentation and samples on this issue are missing while this is quite important feature in my opinion.
If somebody is interested I can share some code how to use it in a CustomHandler.

[opcodewriter]

I'm having issues with this, if anybody could check it out I would appreciate some help: #339