feat(uiView): Fire the $onInit hook

[dgsmith2]

After instantiating the controller, will fire its $onInit if defined.

Closes #2559

[christopherthielen]

I think this looks good.

A couple observations:

• the docs suggest that $onInit is only for components, and only mentions them in the context of DDOs
• the release notes explicitly state the hook is for components/directives
• angular-route does not fire $onInit on its ng-view controllers
• I'd rather not re-implement the logic already found in $compile

That said, I don't see much of a downside.

I'll be curious if ng-view does something similar.

[dgsmith2]

This is a bit contrived, but a downside of NOT doing it is you lose the ability to reuse a (component) controller that implements $onInit in all these extra scenarios and more.

I submitted a similar PR to address it with modals: angular-ui/bootstrap#5509. Currently, there are no objections, but your observations may be worth noting over there as well.

[christopherthielen]

lose the ability to reuse a (component) controller that implements $onInit

As I think about it, the whole point of $onInit it to allow the bindToController or bindings to be done after controller constructor is invoked, and then call $onInit in order to use the bound data.
edit: I found out that this is not the case

I don't think $onInit is useful without some sort of bindings (or $ctrl.$resolve) support.

[dgsmith2]

Are you opposed to an initialization hook in general or one name "$onInit" due to the unmet implications of 1.5 component controllers?

I've found that having a hook at the very least simplifies testing. In situations in which a controller needs to make a request when it is initialized one only needs to mock the service call when testing the hook call.

[christopherthielen]

I'm in favor of the $onInit hook but don't think it's necessary until we support binding to component in some manner.

[petebacondarwin]

It might be worth noting that the new component router has its own hooks. Notably it calls $routerOnActivate when the component has been instantiated and wired up by the ng-outlet (which is equivalent to your ui-view).