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getInitialState() returning something weird followed by setState() has the world's worst error message #397

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petehunt opened this issue Oct 2, 2013 · 4 comments
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getInitialState() returning something weird followed by setState() has the world's worst error message #397

petehunt opened this issue Oct 2, 2013 · 4 comments
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@petehunt
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petehunt commented Oct 2, 2013

See http://jsfiddle.net/nbJVN/

Return a string from getInitialState() and call setState(). You get this amazing error message:

Uncaught Error: Critical assumptions about the merge functions have been violated. This is the fault of the merge functions themselves, not necessarily the callers.
@zpao
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zpao commented Oct 2, 2013

We should probably add an invariant that whatever is returned from getInitialState is in fact an object.

@vjeux
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vjeux commented Oct 2, 2013

Invariant all the things :)

@dkvasnicka
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This also seems to apply when using an array, not the string only. Which makes it a pretty real-world bug IMHO (compared to the weird string scenario).
Or is there a reason you don't want states to be arrays?

@zpao
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zpao commented Dec 12, 2013

This will happen whenever state is anything but an Object (I think there is a check in there for arrays). Since we use merge it needs to be an object, arrays are no good either.

@benjamn benjamn closed this as completed in 77697f2 Jan 2, 2014
benjamn added a commit that referenced this issue Jan 2, 2014
@benjamn
Merge pull request #725 from cpojer/getInitialState-invariant
04ad3bf 
Add invariant to check getInitialState return value. Fixes #397.
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@zpao @vjeux @petehunt @dkvasnicka