transition.abort() causes 500 responses

[arjansingh]

As @rwjblue pointed out in #195, aborting a transition in FastBoot causes a TransitionAborted error to be thrown by the server, resulting in the request failing and the response returning a 500 error.

Here is an example stack trace:

Error: TransitionAborted at handleReject (/code/ember-bugs/dist/fastboot/vendor.js:14132:17)
 at tryCatch (/code/ember-bugs/dist/fastboot/vendor.js:63911:14)
 at invokeCallback (/code/ember-bugs/dist/fastboot/vendor.js:63926:15)
 at publish (/code/ember-bugs/dist/fastboot/vendor.js:63894:9)
 at publishRejection (/code/ember-bugs/dist/fastboot/vendor.js:63829:5)
 at /code/ember-bugs/dist/fastboot/vendor.js:42159:7 at Queue.invokeWithOnError (/code/ember-bugs/dist/fastboot/vendor.js:10447:18)
 at Object.Queue.flush (/code/ember-bugs/dist/fastboot/vendor.js:10502:11)
 at Object.DeferredActionQueues.flush (/code/ember-bugs/dist/fastboot/vendor.js:10310:17)
 at Object.Backburner.end (/code/ember-bugs/dist/fastboot/vendor.js:10665:25)
 at [object Object]._onTimeout (/code/ember-bugs/dist/fastboot/vendor.js:11231:18)
 at Timer.listOnTimeout (timers.js:92:15)

I'll try to look at this when I get some time. If anyone has any thoughts on what might be causing this, please chime in.

[jasonmit]

It believe it's happening here: https://github.com/ember-fastboot/fastboot-express-middleware/blob/master/index.js#L54-L65

Similar to the handling of UnrecognizedURLError, we might want to also call next on TransitionAborted

[jasonmit]

Actually, I'm unsure how we should handle aborted transitions so I closed my related PR. What is the behavior that you are expecting?

[tomdale]

@arjansingh Ping when you get a chance

[arjansingh]

In my opinion the expected behavior on an abort should be to just continue execution of the code.

Aborts are usually followed with a transitionTo, which would result in 307 redirect: https://github.com/ember-fastboot/ember-cli-fastboot/blob/master/app/locations/none.js#L29-L49

If there is no transition then the expected behavior from what I can see is to just render whatever route we are on with the information we have available, like we would for a non-fastbooted page.

Here's the code for abort() for reference: https://github.com/tildeio/router.js/blob/master/lib/router/transition.js#L184-L200

[rwjblue]

Confirm. I do not think an aborted transition should be directly considered an error condition.

[Gaurav0]

@rwjblue Reproduction without explicit transition.abort: https://github.com/Gaurav0/fastboot-issue-202.git

[rwjblue]

I did a bit of investigation into this today (thanks to @Gaurav0 reproduction), and have isolated the issue.

This error is currently (speaking about Ember 2.10+) only occurring when a .transitionTo / .redirectTo is being done asynchronously in afterModel. Doing the redirect in the redirect or model hooks work without an error.

In afterModel the following would work without error:

afterModel() {
  this.transitionTo('something');
}

And this would not:

afterModel() {
  return Ember.RSVP.Promise.resolve()
    .then(() => {
      this.transitionTo('something');
    });
}

The reason for this, is that we currently only allow a transition to be aborted while it is underway (and we use this.get('router').router.activeTransition to track that here), but once afterModel has ran we immediately clear the activeTransition (see here).

[rwjblue]

I commented on ember-learn/ember-api-docs#128 with a more concrete solution over there.