UnchangedValidator

A validator for ActiveModels that checks that attributes have not been modified since the last time the model was saved.

Installation

Add this line to your application's Gemfile:

gem 'unchanged_validator'

And then execute:

$ bundle

Or install it yourself as:

$ gem install unchanged_validator

Running the tests

Install various dependencies:

$ appraisal install

Then, to run the tests:

$ appraisal rspec

Usage

Example

class Person < ActiveRecord::Base
  validates_unchanged :first_name
end

p = Person.new
p.first_name = 'Bob'
p.save
#=> true
p.valid?
#=> true

p.first_name = 'Dave'
p.save
#=> false
p.valid?
#=> false

I18n

To change the default message for all usages of validates_unchanged:

# In config/locales/en.yml
en:
  activerecord:
    errors:
      messages:
        changed: 'cannot be different'

To change the message for a particular attribute of a particular model:

# In config/locales/en.yml
en:
  activerecord:
    models:
      person:
        attributes:
          first_name:
            changed: 'cannot be different'

Options

UnchangedValidator supports all of the common ActiveModel::Validations options:

class Book < ActiveRecord::Base
  validates_unchanged :title, allow_blank: true
  validates_unchanged :author, allow_nil: true
  validates_unchanged :copyright_expirty_date, if: same_edition?
  validates_unchanged :published_date, message: 'cannot be re-released'
  validates_unchanged :foreward, on: :update
  validates_unchanged :publisher, unless: :rebranded?
end