I am still fairly new to rails and activerecord, so please excuse any oversights.

I have 3 models that I'm trying to tie together (and a 4th to actually do the tying) to create a permission scheme using user-defined roles.

class User < ActiveRecord::Base
  has_many :user_projects
  has_many :projects, :through => :user_projects
  has_many :project_roles, :through => :user_projects
end

class Project < ActiveRecord::Base
  has_many :user_projects
  has_many :users, :through => :user_projects
  has_many :project_roles
end

class ProjectRole < ActiveRecord::Base
  belongs_to :projects
  belongs_to :user_projects
end

class UserProject < ActiveRecord::Base
  belongs_to :user
  belongs_to :project
  has_one :project_role
  attr_accessible :project_role_id
end

The project_roles model contains a user-defined role name, and booleans that define whether the given role has permissions for a specific task. I'm looking for an elegant solution to reference that from anywhere within the project piece of my application easily.

I do already have a role system implemented for the entire application. What I'm really looking for though is that the users will be able to manage their own roles on a per-project basis. Every project gets setup with an immutable default admin role, and the project creator gets added upon project creation.

Since the users are creating the roles, I would like to be able to pull a list of role names from the project and user models through association (for display purposes), but for testing access, I would like to simply reference them by what they have access to without having reference them by name.

Perhaps something like this?

def has_perm?(permission, user) # The permission that I'm testing
  user.current_project.project_roles.each do |role|
    if role.send(permission) # Not sure that's right...
      do_stuff
    end
  end
end

I think I'm in over my head on this one because I keep running in circles on how I can best implement this.