Posted under JSF
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Tags Bug, Gotcha, JSF, Tip
Initially this looked very strange. When navigating to a new form, the rendered= methods for the old form were being called again, and were failing due to scoping issues – a new request scope bean was being created causing a null pointer exception in the method as required state had been lost.
This post and also this post on StackOverflow explain the problem. Apparently JSF rechecks the rendered conditions after the submit as part of an attack safeguard. This is what caused recreation of a new bean and the failure.
This behaviour was certainly unexpected, and I have not seen it documented ‘up front’ previously – so it is certainly one to be aware of! This is not the first time I have had issues with the render= attribute.
In my case, resolving issues in creation of conversations solved the problem – once I had conversations propagating properly, everything worked correctly and the state was present for the extra calls to the rendered= methods.
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