refactor(accordion): use @ContentChildren instead of @Query

[pkozlowski-opensource]

@query is going away: angular/angular#4919

[pkozlowski-opensource]

BTW: we can't remove child->parent relationship (and thus circular deps...) till there is a solution similar to angular/angular#5467

[Foxandxss]

So I never did this because they are both broken (accordion in master and your PR is equally broken).

We need those changes @robwormald proposed to listen for children stuff.

[pkozlowski-opensource]

So I never did this because they are both broken (accordion in master and your PR is equally broken).

Did you try this stuff with Beta.0? I see it working on my end, will put together a plunker if needed.

[Foxandxss]

try plunker try. There is some race conditions that happens in some places.

[pkozlowski-opensource]

@Foxandxss here is a plunker with a version from this PR: https://plnkr.co/edit/7GarmofzfeG01L8RtEgU?p=preview

There is some race conditions that happens in some places.

Do you have more info? Do you reproduce those in the plunker I've linked?

[pkozlowski-opensource]

So, I've spent a couple days trying to dig deeper into this issue / general design of accordion-like components. As a result I will be sharing a doc with the angular team shortly with proposals on how to change the core of the framework. At the same time I believe that I've found an acceptable solution with the beta.7 version of the framework. It requires some refactoring to the existing code / design on our end, but I believe that those refactorings go in the right direction.

Closing this PR, will send another one shortly.