Rails model validation on create and update only

问题:

If I want to have validation only on create, then I can do

validates_presence_of :password, :on => :create

But how do I say on create and update? I tried this but it didn't work:

validates_presence_of :password, :on => [ :create, :update ]

Do I have to define the validation two times?

回答1:

By default, the validations run for both create and update. So it should be just:

validates_presence_of :password

The :on key just allows you to choose one of them.

回答2:

Only write:

validates_presence_of :password

No need...

on => :create

回答3:

You can use this when you need to disable the validation on some specific operations, such as delete.