Differnet link to depending on class type.

link_to.rb

<%  @pg_searches.each do |pg_search| %>
  <% if pg_search.searchable.class == Book %>
    <p> <%= link_to pg_search.searchable.title, pg_search.searchable %></p> 
  <% elsif pg_search.searchable.class == Chapter %>
    <p> <%= link_to pg_search.searchable.title, [pg_search.searchable.book, pg_search.searchable] %></p>
  <% end %>
<% end %>