cancancan alert and notice messages

Question

Question from a newbie with Rails.

I have this:

rescue_from CanCan::AccessDenied do |exception|
 respond_to do |format|
   format.json { head :forbidden, content_type: 'text/html' }
   format.html { redirect_to main_app.root_url, notice: exception.message }
   format.js   { head :forbidden, content_type: 'text/html' }
 end
end

in application_controller.rb

I have tried several ways to add to or to replace the exception message in a specific case such as

  def show
    authorize! :read, @post, :alert => "Please log in to access this page"

    @post = Post.find(params[:id])
    @posts = Post.order("created_at DESC").limit(4).offset(1)
  end

Here I use alert and I have no alert message displayed. Trying notice doesn't replace the exception message from the Cancan rescue.

I've also tried this:

          <% if user_signed_in? %>
            <% if can? :update, @post %>
              <p><%= link_to "modify", edit_post_path(@post.id) %></p>
            <% else %>
              <%= flash[:alert] = 'Please log in to access this page' %>
            <% end %>
          <% end %>

in my show.html.erb page, which I find less dry than my code in the post_controller.rb above.

Before I try some nice code with css ot JS, I'd like to see at least something basic happening. Where does the problem come from ?

Of course, I have these lines in my pages:

<p class="notice"><%= notice %></p>
<p class="alert"><%= alert %></p>

Answer 1

Testing out on a new rails project, the following would make yours work:

app/controllers/SOMECONTROLLER.rb

def show
  authorize! :show, @post, message: 'Please log in to access this page'
  # and not...
  # authorize! @post, message: 'Please log in to access this page'
  # ...
end