[fixed] Now execute willTransition* hooks even if only query part was changed

[vladimir-vg]

Upgraded to 0.11 and discovered that params now passed a bit differently. I had rewritten my app code to use willTransitionTo instead of old componentWillReceiveProps.

I'm using query params for filtering results. Surprisingly discovered that now query changes doesn't fire hooks, while still producing transition.

This pull request fixes that.

[ryanflorence]

are you saying componentWillReceiveProps is not called anymore on query changes?

[mjackson]

@vladimir-vg Can you please write a test that demonstrates the problem you're trying to address with this PR?

[vladimir-vg]

@rpflorence yes, exactly. Well, componentWillReceiveProps is not called at all, because now we access params and queries using State mixin and willTransition* hooks.

And these willTransition* hooks ignored if only query part was changed.

@mjackson, I will write tests, but cannot do it right now -- probably in 2-3 days, when I reach my computer.

[vladimir-vg]

@mjackson added test that demonstrates problem. If you comment added changes, test will fail.

[ryanflorence]

@vladimir-vg ignoring the potential merge of this pull request, you can pass the params/query down your view hierarchy to get the componentWillReceiveProps hook to fire (and therefore keep your app similar to how it used to be) by using the technique described here: https://github.com/rackt/react-router/blob/master/UPGRADE_GUIDE.md#thispropsparams-and-thispropsquery

[ryanflorence]

wait a sec, look at the master-detail example, componentWillReceiveProps is firing there.

https://github.com/rackt/react-router/blob/v0.11.1/examples/master-detail/app.js#L92-L94

That's how it knows to get a different contact from the store.

[ryanflorence]

oh ... its the query that doesn't trigger componentWillReceiveProps anymore I guess?

Maybe it should.

[vladimir-vg]

@rpflorence Probably I unintentionally mislead you. I actually don't know does it fire componentWillReceiveProps. I don't care, because I do not pass params and query to Handler via props anymore. Actually it should fire.

According to 0.10 release params and query doesn't passed to Handler by default. So I do not use them in old style anymore. I get them through State mixin and by willTransition* hooks. And I had a problem with latter.

I'm aware of available workaround.

[ryanflorence]

thanks!

[vladimir-vg]

You're welcome.

[mjackson]

There are a few problems with 0c3c75d, namely:

1. There is a bug that occurs when state.routes is empty. See Uncaught TypeError: Cannot read property 'length' of undefined #623
2. This only triggers the transition hooks in the leaf route handler when the query changes, not the rest of the hierarchy

The first issue isn't a huge one. I can fix it easily.

The bigger issue is the second. If we're going to trigger transition hooks when the query changes, we should probably trigger them in every route handler in the hierarchy, not just the leaf route. This makes it even more obvious how the transition hooks are different from componentWillMount and friends: because they don't necessarily have anything to do with components mounting and unmounting. Instead, they're strictly concerned with routing changes.

If you guys can agree on these points I think I can make a patch today.

[vladimir-vg]

@mjackson As I can see you already fixed the problem. Everything ok now, right?
Sorry, my bad.

[mjackson]

@vladimir-vg Yeah, np :)