After abilities are defined, you can use the
can? method in the controller or view to check the user's permission for a given action and object.
can? :destroy, @project
cannot? method is for convenience and performs the opposite check of
cannot? :destroy, @project
Checking with Class
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 %>
Important: If a block or hash of conditions exist they will be ignored when checking on a class, and it will return
true. For example:
can :read, Project, :priority => 3 can? :read, Project # returns true
It is impossible to answer this
can? question completely because not enough detail is given. Here the class does not have a
priority attribute to check on.
Think of it as asking "can the current user read a project?". The user can read a project, so this returns
true. However it depends on which specific project you're talking about. If you are doing a class check, it is important you do another check once an instance becomes available so the hash of conditions can be used.
The reason for this behavior is because of the controller
index action. Since the
authorize_resource before filter has no instance to check on, it will use the
Project class. If the authorization failed at that point then it would be impossible to filter the results later when Fetching Records.
That is why passing a class to
can? will return
The code answering the question "can the user update all the articles?" would be something like:
Article.accessible_by(current_ability).count == Article.count