require 'active_support/core_ext/object/blank' module ActiveModel module Validations module ClassMethods # Validates that the specified attributes are not blank (as defined by Object#blank?). Happens by default on save. Example: # # class Person < ActiveRecord::Base # validates_presence_of :first_name # end # # The first_name attribute must be in the object and it cannot be blank. # # If you want to validate the presence of a boolean field (where the real values are true and false), # you will want to use validates_inclusion_of :field_name, :in => [true, false]. # # This is due to the way Object#blank? handles boolean values: false.blank? # => true. # # Configuration options: # * message - A custom error message (default is: "can't be blank"). # * on - Specifies when this validation is active (default is :save, other options :create, # :update). # * if - Specifies a method, proc or string to call to determine if the validation should # occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). # The method, proc or string should return or evaluate to a true or false value. # * unless - Specifies a method, proc or string to call to determine if the validation should # not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). # The method, proc or string should return or evaluate to a true or false value. # def validates_presence_of(*attr_names) configuration = attr_names.extract_options! # can't use validates_each here, because it cannot cope with nonexistent attributes, # while errors.add_on_empty can validate configuration do |record| record.errors.add_on_blank(attr_names, configuration[:message]) end end end end end