title: Cancan :create ability
body: <p>I have the following code:</p>
  
  <pre><code>#/app/models/users/user.rb
  class Users::User &lt; ActiveRecord::Base
    has_many :phones, class_name: "Users::Phone"
  end
  
  #/app/models/users/phone.rb
  class Users::Phone &lt; ActiveRecord::Base
    belongs_to :user, class_name: "Users::User"
    attr_accessible :phone
  end
  
  
  #/app/models/ability.rb
  class Ability
    include CanCan::Ability
  
    def initialize(user)
  
      can :read, :all
  
      unless user.nil? #logged_in
        if user.is? :admin
          can :manage, :all
        else
          can :create, Users::Phone, user_id: user.id
        end
      end
  
    end
  end
  </code></pre>
  
  <p>I wanna check ability for create only their own phones for users</p>
  
  <pre><code>#/app/views/users/users/show.html.slim
  - if can? :create, Users::Phone.new
    a[href="#{new_user_phone_path(@user)}"] Add phone
  </code></pre>
  
  <p>Thats does not work, because I should pass user_id to phone model (like <code>Users::Phone.new user_id: user.id</code>), but I can't do that since Phone's mass assignment.</p>
  
  <p>So how I can check <code>:create</code> phones ability for users?</p>