Avoid setState on unmounted components

[srph]

So, I'm using react-resolver with react-router for permissions. So, if a user doesn't pass a certain requirement, they're redirected somewhere. This means that I don't really want to put something to the props.

I just want to avoid errors such as these:

Warning: setState(...): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op. Please check the code for the Resolver component.

Warning: setState(...): Cannot update during an existing state transition (such as within `render`). Render methods should be a pure function of props and state.

[ratson]

Encountered the same problem, @ericclemmons is there any way we could avoid it?

Update: Just have read https://facebook.github.io/react/blog/2015/12/16/ismounted-antipattern.html Seems it is the solution that react-resolver could implement to solve the problem.

[ericclemmons]

I'm curious if this is solved in react-router 2.0.

This exists because resolution happens, you attempt to redirect (which should be synchronous and immediate), but the router seems to trigger the redirect in the next event loop/tick/whatever, meaning the component still renders, mounts, etc. and then the redirect happens.

I'm all for a fix, but curious if this has been solved with the rewrite first.

[ratson]

This line could be executed after unmount regardless redirects, as promise is resolved asynchronously.

AFAIK, that's why the blog post suggest to cancelling the promise before unmount. Or am I missing something?

[ericclemmons]

I suppose the only/best way around this is to track if the component is still mounted or not before calling setState...