Question

How does one fragment cache comments with a session information? For example:

  <% cache "song_#{@song.id}_comments" do %>
    <ul>
        <% @comments.each do |comment| %>

          <li class="clearfix">
            <p><%= comment.comment %></p>

            <% if can? :destroy, comment %>
              <span>&middot;</span><%= link_to 'delete', comment_path(comment), :confirm => 'Are you sure?', :method => :delete, :remote => true %>
            <% end %>

          </li>
        <% end %>
    </ul>
  <% end %>

A delete link displays if a user owns the comment. But since, this is cached. It shouldn’t show up for other users.

Answer 1

I think it is not possible to have session-based logic in the fragment cache unless you make that information part of the key, which kind of defeats the purpose of caching.

One possible way is to use client-based logic to add delete-link dynamically if the comment is owned by the user.
For example, you can embed a hidden_field – owner_id for each comment. And then, for each rendering, apart from the cached comments (with owner-ids), you can have another hidden field – current user id. JS can then add the delete link for all comments that the user is the owner of.