Call a specified method on a specific life cycle event.
Here is an example:
require "granite/adapter/pg"
class Post < Granite::Base
  connection pg
  before_save :upcase_title
  column id : Int64, primary: true
  column title : String
  column content : String
  timestamps
  def upcase_title
    if title = @title
      @title = title.upcase
    end
  end
end
You can register callbacks for the following events: