Acts As Immutable

A Rails plugin that will ensure an ActiveRecord object is immutable once saved. Optionally, you can specify attributes to be mutable if the object is in a particular state (block evaluates to true).

Authored by: NuLayer Inc. / www.nulayer.com

Install

gem 'acts_as_immutable', github:'Dealermade/acts_as_immutable'

Usage examples

Ex. 1 All attributes will be immutable

class PaymentTransaction < ActiveRecord::Base
    acts_as_immutable
end

Ex. 2 All attributes will be immutable except 'paid', ie. if the invoice is still outstanding

class Invoice < ActiveRecord::Base
    acts_as_immutable :paid do
        paid == false
    end
end

Ex. 3 Objects are immutable unless the subscription is active or free in which case changes can be made to: status, free and updated_at

class Subscription < ActiveRecord::Base
    acts_as_immutable :status, :free, :updated_at do
        free? || active?
    end

    def active?
        status == "active"
    end
end

> sub = Subscription.new
> sub.status = "active"
> sub.free = false
> sub.start_date = Time.now
> sub.end_date = Time.now + 1.year
> sub.save
=> true
> sub.start_date = Time.now + 1.week
=> ActiveRecord::ActsAsImmutableError: start_date is an immutable attribute

> sub.update_attributes({ :start_date => Time.now + 1.week })
=> ActiveRecord::ActsAsImmutableError: start_date is an immutable attribute

> sub.status = "cancelled"
> sub.save
=> true

Testing

Tested on Rails 4.2.0. To run the tests, invoke rake or guard.

License (MIT)

Copyright (c) 2009 NuLayer Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.