CanCanCan::Masquerade

Put on a mask and pretend! CanCanCan::Masquerade allows your objects to pretend to be other objects when checking permissions.

This gem was originally designed with the goal of allowing ViewModels to act as Models in a Ruby on Rails application. The implementation is simple enough that it can be applied to pretty much any object you like.

Add this line to your application's Gemfile:

gem 'cancancan_masquerade'

And then execute:

$ bundle

Or install it yourself as:

$ gem install cancancan_masquerade

Include Masquerade in your ability class!

class Ability
  include CanCan::Ability
  include CanCanCan::Masquerade

  # ... your permissions, as usual
end

From here, we're operating on other objects in your project. Only that one modification needs to be made to your ability class for this to work.

If the object you'd like to masquerade as is an instance variable of the current object, simply specify it as a symbol (similar to delegating to an instance variable in Rails):

class MaskedDancer
  extend CanCanCan::Masquerade::InheritPermissions

  inherit_permissions_from :@dancer

  # ... rest of your class
end

If the object you'd like to masquerade as can be accessed via a property of the current object, pass the name of the method as a symbol:

class MaskedDancer
  extend CanCanCan::Masquerade::InheritPermissions

  inherit_permissions_from :partner

  # ... rest of your class
end

If neither of the above work and the current object can be mapped into the object you wish to pretend to be, you can specify the class name and the mapping directly:

class MaskedDancer
  extend CanCanCan::Masquerade::InheritPermissions

  inherit_permissions_from Dancer,
                           mapping: { name: :@name,
                                      type: :type
                                    }

  # ... rest of your class
end

The mapping must be a hash! Values that are symbols will be checked against defined methods and instance variables for mapping. If neither match or the value is not a symbol, it will be passed as is.

If the new object can't be built using one of these methods, you can pass a block that will be called when the object is needed for checking permissions:

class MaskedDancer
  extend CanCanCan::Masquerade::InheritPermissions

  build_permission_instance do
    # build your permission object here
  end
end

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/chall8908/cancancan_masquerade. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the CancancanMasquerade project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.