Changing default error messages in Rails

Our client has d开发者_如何学运维ecided that they would like all blank AR error messages to be changed from "can't be blank" to "must be completed" throughout the entire app.

What's the easiest Rails'y way of doing this?

Use config/locales/en.yml

Specifically, put the following in that file:

en:
  activerecord:
    errors:
      messages:
        blank: "must be completed"