Protected Attributes Continued

This is the community continued version of protected_attributes for Rails 5+. The Rails team dropped this feature and switched to strong_parameters. However some applications simply cannot be upgraded or the reduced granularity in params management is a non-issue. To continue supporting this feature going forward we continue the work here.

Protect attributes from mass-assignment in Active Record models. This gem adds the class methods attr_accessible and attr_protected to declare white or black lists of attributes.

Installation

Add this line to your application's Gemfile:

gem 'protected_attributes_continued'

And then execute:

bundle install

Usage

Mass assignment security provides an interface for protecting attributes from end-user injection. This plugin provides two class methods in Active Record classes to control access to their attributes. The attr_protected method takes a list of attributes that will be ignored in mass-assignment.

For example:

attr_protected :admin

attr_protected also optionally takes a role option using :as which allows you to define multiple mass-assignment groupings. If no role is defined then attributes will be added to the :default role.

attr_protected :last_login, as: :admin

A much better way, because it follows the whitelist-principle, is the attr_accessible method. It is the exact opposite of attr_protected, because it takes a list of attributes that will be mass-assigned if present. Any other attributes will be ignored. This way you won’t forget to protect attributes when adding new ones in the course of development. Here is an example:

attr_accessible :name
attr_accessible :name, :is_admin, as: :admin

If you want to set a protected attribute, you will have to assign it individually:

params[:user] # => {name: "owned", is_admin: true}
@user = User.new(params[:user])
@user.is_admin # => false, not mass-assigned
@user.is_admin = true
@user.is_admin # => true

When assigning attributes in Active Record using attributes= the :default role will be used. To assign attributes using different roles you should use assign_attributes which accepts an optional :as options parameter. If no :as option is provided then the :default role will be used.

You can also bypass mass-assignment security by using the :without_protection option. Here is an example:

@user = User.new

@user.assign_attributes(name: 'Josh', is_admin: true)
@user.name # => Josh
@user.is_admin # => false

@user.assign_attributes({ name: 'Josh', is_admin: true }, as: :admin)
@user.name # => Josh
@user.is_admin # => true

@user.assign_attributes({ name: 'Josh', is_admin: true }, without_protection: true)
@user.name # => Josh
@user.is_admin # => true

In a similar way, new, create, create!, update_attributes and update_attributes! methods all respect mass-assignment security and accept either :as or :without_protection options. For example:

@user = User.new({ name: 'Sebastian', is_admin: true }, as: :admin)
@user.name # => Sebastian
@user.is_admin # => true

@user = User.create({ name: 'Sebastian', is_admin: true }, without_protection: true)
@user.name # => Sebastian
@user.is_admin # => true

By default the gem will use the strong parameters protection when assigning attribute, unless your model has attr_accessible or attr_protected calls.

Errors

By default, attributes in the params hash which are not allowed to be updated are just ignored. If you prefer an exception to be raised configure:

config.active_record.mass_assignment_sanitizer = :strict

Any protected attributes violation raises ActiveModel::MassAssignmentSecurity::Error then.

Contributing

For quicker feedback during gem development or debugging feel free to use the provided rake console task. It is defined within the Rakefile.

We test multiple versions of Rails using the appraisal gem. Please use the following steps to test using appraisal.

1. bundle exec appraisal install
2. bundle exec appraisal rake test

Credits

Created & Maintained by Weston Ganger - @westonganger

Originally forked from the dead/unmaintained protected_attributes gem by the Rails team.

A Simple and Similar strong_params Alternative

While I do utilize this gem in some legacy projects. The latest approach I have adopted is similar to this gem but only utilizes Rails built-in strong_params which is a much more future proof way of doing things. The following is an example implementation.

### Model
class Post < ActiveRecord::Base
  has_many :comments

  accepts_nested_attributes_for :comments, allow_destroy: true
  
  def self.strong_params(params)
    params.permit(:post).permit(*PERMITTED_ATTRIBUTES)
  end
  
  PERMITTED_ATTRIBUTES = [
    :id,
    :name,
    :content,
    :published_at,
    {
      comments_attributes: Comment::PERMITTED_ATTRIBUTES,
    }
  ].freeze
  
end

### Controller
class PostsController < ApplicationController
  def create
    @post = Post.new(Post.strong_params(params))
    
    @post.save

    respond_with @post
  end

  def update
    @post = Post.find(params[:id])

    @post.update(Post.strong_params(params))

    respond_with @post
  end
end