Anonymizable

Anonymizable adds the ability to anonymize or delete data in your ActiveRecord models. A good use case for this is when you want to remove user accounts but for statistical or data integrity reasons you want to keep the actual records in your database.

Anonymizer supports all 2.x versions of Ruby and all Rails versions between 3.2.x and 4.x.

gem 'anonymizable'

and run bundle install from your shell.

class User < ActiveRecord::Base

  anonymizable do
    attributes :first_name, :last_name
  end

end

This adds an instance method User#anonymize! which in this case just nullifies the first_name andlast_name database columns.

The anonymize! method is defined as private by default, but you can make it public by passing the public option:

  anonymizable public: true do
    attributes :first_name, :last_name
  end

By passing to attributes a hash as the last argument, you can anonymize columns using a Proc or instance method.

anonymizable public: true do

  attributes  :first_name, :last_name,
              email: Proc.new { |u| "anonymized.user.#{u.id}@foobar.com" }, 
              password: :random_password
end

In this example, the email column will be anonymized by calling the block and passing the User object. The password column will be anonymized using the return value of User#random_password, which can be defined as either a public or private instance method. The user object is not passed as an argument in this case, but can be accessed by self.

ActiveRecord associations can either be anonymized, destroyed, or deleted.

anonymizable public: true do

  attributes  :first_name, :last_name,
              email: Proc.new { |u| "anonymized.user.#{u.id}@foobar.com" }, 
              password: :random_password

  associations do
    anonymize :posts, :comments
    delete    :avatar, :likes
    destroy   :images
  end

end

In the example above, the anonymize! method will be called on each Post and Comment association. As such, anonymization must be defined on both of these classes:

class Post < ActiveRecord::Base

  anonymizable :user_id

end

class Comment < ActiveRecord::Base

  anonymizable :user_id

end

In this case, the user_id column is nullified on any of the user's posts or comments.

All operations on columns and attributes are performed in a database transaction which will rollback all changes if an error occurs during anonymization.

You can declare a Proc or method to use as a guard against anonymization. If the Proc or method returns ruby false or ruby nil, anonymization will short circuit.

  anonymizable public: true do
    only_if :can_anonymize?

    attributes  :first_name, :last_name,
                email: Proc.new { |u| "anonymized.user.#{u.id}@foobar.com" }, 
                password: :random_password

    associations do
      anonymize :posts, :comments
      delete    :avatar, :likes
      destroy   :images
    end

  end

  def can_anonymize?
    !admin?
  end

You can prohibit the deletion of objects on which anonymizable is configured by passing the raise_on_delete option:

  anonymizable raise_on_delete: true do

    attributes  :first_name, :last_name,
                email: Proc.new { |u| "anonymized.user.#{u.id}@foobar.com" }, 
                password: :random_password

    associations do
      anonymize :posts, :comments
      delete    :avatar, :likes
      destroy   :images
    end

  end

  > user.delete
  Anonymizable::DeleteProhibitedError: destroy is prohibited on #<User:0x007f8d125e4948>

  > user.destroy
  Anonymizable::DestroyProhibitedError: destroy is prohibited on #<User:0x007f8d125e4948>

You can declare callbacks that run after anonymization is complete.

anonymizable public: true do

  attributes  :first_name, :last_name,
              email: Proc.new { |u| "anonymized.user.#{u.id}@foobar.com" }, 
              password: :random_password

  associations do
    anonymize :posts, :comments
    delete    :avatar, :likes
    destroy   :images
  end

  after :email_admin, Proc.new { |original_attrs| log("Attributes changed: #{original_attrs}") }
end

Each method or Proc is passed the value of the object's pre-anonymization attributes as a hash. You would define a method on ```User`` that receives the attribute hash:

 def email_admin(original_attributes)
    AdminMailer.user_anonymized(original_attributes["email"])
  end

It is worth noting that these callbacks are run after the database transaction commits, so an error in a callback does not trigger a database rollback.

As intimated in the Post and Comment examples above, you can call anonymize without a block, but rather just with an array of columns to nullify and/or anonymization hash. In this case the Model#anonymize! will be private.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

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