Object Attorney

This gem allows you to create use cases with ActiveModel validations and keep your model clean.

1) Basic Usage

class User < Struct.new(:title, :first_name, :last_name)
end

class UserValidator < ObjectAttorney::Base
  validates_presence_of :first_name

  validate :last_name_present

  def last_name_present(user)
    return if user.last_name.present?

    user.errors.add(:last_name, :blank)
  end
end

@user = User.new

UserValidator.new(@user).valid? # false

@user.errors.messages # { first_name: ["can't be blank"], last_name: ["can't be blank"] }

2) Custom Usage

class User < ActiveRecord::Base
end

class UserValidator
  include ObjectAttorney

  defend :user

  validates_presence_of :first_name, if: :last_name_is_present

  attr_accessor :user

  def initialize(user)
    @user = user
  end

  def last_name_is_present(user)
    user.last_name.present?
  end
end

@user = User.new(last_name: 'Snow')

UserValidator.new(@user).invalid? # true

@user.errors.messages # { first_name: ["can't be blank"] }