rails 笔记

The following methods trigger validations, and will save the object to the database only if the object is valid:

• create
• create!
• save
• save!
• update
• update_attributes
• update_attributes!

The bang versions (e.g. save!) raise an exception if the record is invalid. The non-bang versions don’t: save and update_attributes return false, create and update just return the objects.