How can I use callback to check before status transition?

[luoxi001713]

Scenario:
Status A - > status B, I want to check if a field is valid before transition.

I know there is a before_EVENT, but I don't know how to control don't let the status from A to B in this function.

Thanks

[suerta-git]

I saw that there is a Cancel() method in event object you can call it in callbacks

[maxekman]

@luoxi001713 Is your question answered by @suerta-git?