Return a promise from $location.path (and search) to detect if the change was cancelled

[Shazwazza]

Currently if you do a $location.path("/blah") (with optional .search) you have no way of knowing if someone has cancelled your attempt at changing the path by using a listener on $locationChangeStart + event.preventDefault()

Currently there is no event for $locationChangeFailed so it's near impossible to know if you path change attempt was cancelled without some hackery or custom events that are emitted in the code that is calling event.preventDefault().

[caitp]

How exactly would a location change fail? It doesn't make an http request or anything, so its not really clear

[pkozlowski-opensource]

@caitp I guess this is about the fact that the location change can be canceled. So it doesn't fail but can be prevented. It is true that in this case we are not propagating any location change error:
https://github.com/angular/angular.js/blob/master/src/ng/location.js#L738

[caitp]

Yeah but nothing in core cancels it, and presumably if a user cancels it, they know what they're doing. If a module cancels it, they might get another way, like $routeChangeError (although ngRoute only cares about $locationChangeSuccess) --- It doesn't hurt to add another event, but that codepath is really rare/never happens

[Shazwazza]

Unfortunately route change error doesn't fire when it's cancelled either.

Sent from my phone

[caitp]

Because nothing ever cancels it, basically (it's really a situation where if you cancel it, you know that you cancelled it)

[Shazwazza]

What I'm saying is that if something cancels the location change, there is
no way to know. The route change error event does not fire, hence the
reason for logging this issue.

The problem is that we have a very large app, some ui gets shown, a user
clicks on a button,and tries to change the location. Another panel cancels
the location change because a form is dirty, the panel that the user
clicked the button on needs to close.

I've solved this by raising a custom event so the code that tried to change
the location knows that it was cancelled. Just seems that of the
location.path could return a promise as one of its properties to let the
caller know if it was successful or not would be more ideal. Or if the
route failed event fired, that'd work as well but is less ideal.

Sent from my phone