Root Route inits its handler twice about react-router HOT 13 CLOSED

Yeah, that seems weird.

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On Jul 9, 2014, at 2:14 AM, Aliaksei [email protected] wrote:

It seems now that the root hander will be inited and rendered twice, because root Route calls render first time on initial and the second time after parsing URL and setState. It means Route creates two instances of handler and any functionality in render and componentDidMount is called twice almost at the same time, what is totally confusing and can lead to strange bugs.

// in each controller
componentDidMount: function() {
console.log(name);
}

// output
FrontController
FrontController
PageController
SubPageController
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This is expected behavior. Your render function shouldn't have weird side effects.

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@mjackson can you give a quick explanation on why this is expected?

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It's expected because we need some time to run the willTransitionTo hooks. We don't know the state until after they run. If we were to set state immediately, users could see a flash of something they're not supposed to, like a page that requires auth.

But anyway, your render function should be able to be called many times without creating side effects, so this shouldn't be an issue.

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oh that's right, thanks, was not firing on all cylinders for a minute there.

On Wed, Jul 9, 2014 at 11:04 AM, Michael Jackson [email protected]
wrote:

It's expected because we need some time to run the willTransitionTo
hooks. We don't know the state until after they run. If we were to set
state immediately, users could see a flash of something they're not
supposed to, like a page that requires auth.

But anyway, your render function should be able to be called many times
without creating side effects, so this shouldn't be an issue.

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#77 (comment)
.

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Is it not possible to render nothing while waiting for willTransitionTo hooks on the initial render?

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@spicyj The idea is that this.props.activeRoute will be undefined, so when you use it in your render function, you are essentially rendering nothing.

The other option would be to somehow tap into React.renderComponent to stop it from trying to render something until we're ready, or to possibly create our own renderComponent method which we used to have, but I'd like to avoid.

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sure, just branch in render on whatever you're waiting for, probably some state in a store somewhere, or props.activeRoute

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Maybe I'm not understanding still, but why does the root component (FrontController in the above example) need to be rendered before the URL is parsed? Something like:

render: function () {
  if (!this.state.path) {
    return null;
  }
  return this.props.handler(computeHandlerProps(this.state.matches || [], this.state.activeQuery));
}

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@spicyj Doesn't React 0.10 get mad if you return null from render?

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BTW, I'd love to be able to return null, and in fact we tried that approach in an earlier version of this lib. But as I recall React threw an Error.

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Sorry, you're right; it does. You could return <div /> until React 0.11 comes out.

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@spicyj That's a good idea. I think it will prevent a lot of confusion. Looking forward to 0.11! :D

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