Given the following Model, how to determine the User's Role?

Question

Given the following model:

class User < AR::B 
  has_many :permissions 
  has_many :projects, :through => :permissions 
end 
class Project < AR::B 
  has_many :permissions 
  has_many :users, :through => :permissions 
end 
class Role < AR::B 
  has_many :permissions 
end 
class Permission < AR::B 
  belongs_to :user 
  belongs_to :project 
  belongs_to :role 
end

In the user.rb model,,, how can I obtain the user's permission for the project?

Something like self.permissions.role ?

Thanks!

Answer 1

You could add an instance method to the User model that took the project as an argument and returned the permission.

class User < AR
  def permission_for_project(project)
    permissions.find_by_project_id(project.id)
  end

  def role_for_project(project)
    permission = permissions.find_by_project_id(project.id)

    permission.role unless permission.nil?
  end
end

Then use it like:

user = User.find(n)
project = Project.find(n)

permission = user.permission_for_project(project)

role = user.role_for_project(project)

Answer 2

(the_role = user.permissions.find(:first, project_id => project_id).role) && 
   the_role.name

Should look up the (first) permission that the user has for that project and get the role. If there is a role then it will return the name, if not it will return nil.