1 after_update callback is wrapped in transaction means:no matter exception occurs during saving an existing record, or in the after_update method body,both the existing record and record manipulation in the after_update body are all rollbacked?
2 class Book < ActiveRecord::Base has_many :pages validates_associated :pages validates_presence_of :name end
validate_associated means: when i invoke book.save to save book and it's associations,no matter invalidation occurs during saving book self or saving any association,both book and all the associations don't be saved?
I don't understand these from document.can you help me to make it sure? Thanks!