RoleModel is the framework agnostic, efficient and declarative way to do (user) roles. Assigned roles will be efficiently stored as a bitmask directly into your model within a configurable attribute.

It works like this:

# given a User class with a roles_mask attribute
require 'rubygems'
require 'role_model'

class User
  attr_accessor :roles_mask   # just for demo purposes
  # in real life this would usually be a persistent attribute,
  # e.g. if your User model is persisted in a SQL-DB add an integer
  # column named roles_mask to your users table -- just remove/replace
  # above attr_accessor line with whatever is needed for your
  # persistence solution

  include RoleModel

  # if you want to use a different integer attribute to store the
  # roles in, set it with roles_attribute :my_roles_attribute,
  # :roles_mask is the default name
  roles_attribute :roles_mask

  # declare the valid roles -- do not change the order if you add more
  # roles later, always append them at the end!
  roles :admin, :manager, :author
end

#
# Test drive (check the RDoc or source for additional finesse)
#

>> u = User.new
=> #<User ...>

# role assignment
>> u.roles = [:admin]  # ['admin'] works as well
=> [:admin]

# adding roles (remove via delete or re-assign)
>> u.roles << :manager
=> [:admin, :manager]

# querying roles...

# get all valid roles that have been declared
>> User.valid_roles
=> [:admin, :manager, :author]

# ... retrieve all assigned roles
>> u.roles # also: u.role_symbols for DeclarativeAuthorization compatibility
=> [:admin, :manager]

# ... check for individual roles
>> u.has_role? :author  # has_role? is also aliased to is?
=> false

# ... check for multiple roles
>> u.has_any_role? :author, :manager  # has_any_role? is also aliased to is_any_of?
=> true

>> u.has_all_roles? :author, :manager  # has_all_roles? is also aliased to is?
=> false

# see the internal bitmask representation (3 = 0b0011)
>> u.roles_mask
=> 3

# see the role mask for a certain role(s)
>> User.mask_for :admin, :author
=> 5

Once you have included RoleModel, your model is perfectly fit to be used together with a role-based authorization solution, such as github.com/ryanb/cancan or github.com/stffn/declarative_authorization .

gem install role_model

Whenever I introduce a role-based authorization scheme into a project, the code gets coupled somehow to the available roles. So it usually does not make any sense to have a separate Role model stored within the database. This Role model will contain a predefined set of roles anyhow – changing that set will need to be reflected within the authorization code. Putting the available roles right into the model that actually uses them, makes things much easier and efficient.

• Fork the project.

• Make your feature addition or bug fix.

• Add tests for it. This is important so I don’t break it in a future version unintentionally.

• Commit, do not mess with Rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)

• Send me a pull request. Bonus points for topic branches.

RoleModel is an implementation of the Role Based Authorization scheme proposed by Ryan Bates (wiki.github.com/ryanb/cancan/role-based-authorization).

Copyright © 2010 Martin Rehfeld. See LICENSE for details.