This module is automatically included into all controllers. It also makes the “can?” and “cannot?” methods available to all views.
# File lib/cancan/controller_additions.rb, line 290 def self.included(base) base.extend ClassMethods base.helper_method :can?, :cannot?, :current_ability end
Use in the controller or view to check the user’s permission for a given action and object.
can? :destroy, @project
You can also pass the class instead of an instance (if you don’t have one handy).
<% if can? :create, Project %> <%= link_to "New Project", new_project_path %> <% end %>
If it’s a nested resource, you can pass the parent instance in a hash. This way it will check conditions which reach through that association.
<% if can? :create, @category => Project %> <%= link_to "New Project", new_project_path %> <% end %>
This simply calls “can?” on the current_ability. See CanCan::Ability#can?.
# File lib/cancan/controller_additions.rb, line 374 def can?(*args) current_ability.can?(*args) end
Convenience method which works the same as “can?” but returns the opposite value.
cannot? :destroy, @project
# File lib/cancan/controller_additions.rb, line 382 def cannot?(*args) current_ability.cannot?(*args) end
Creates and returns the current user’s ability and caches it. If you want to override how the Ability is defined then this is the place. Just define the method in the controller to change behavior.
def current_ability # instead of Ability.new(current_user) @current_ability ||= UserAbility.new(current_account) end
Notice it is important to cache the ability object so it is not recreated every time.
# File lib/cancan/controller_additions.rb, line 351 def current_ability @current_ability ||= ::Ability.new(current_user) end