Aitor Fernández, Freelance Web Design and Programmer, Graphic Design.

Part of the code that generates dynamically navigating sections. In Enerpal Documentary use a acts_as_nested set. A nested set is a smart way to implement an ordered tree that allows for fast, non-recursive queries.

        # Methods added to this helper will be available to all templates in the application.
        module ApplicationHelper
          
          def tree_select( acts_as_tree_set, init = true, &block )
            if acts_as_tree_set.size > 0
              ret = ''
        
              acts_as_tree_set.collect do |item|
                next if item.parent_id && init
                ret += '<option value="' + item.id.to_s + '">'
                ret += item.level.to_s + ' -' + ( '-' * item.level ).to_s + ' '
                ret += yield item
                ret += '</option>'
                ret += tree_select( item.children, false, &block ) if item.children.size > 0
              end
              
              ret += ''
            end
        
          end
          
          def tree_ul( acts_as_tree_set, init = true, &block )
            if acts_as_tree_set.size > 0
              ret = '<ul>'
        
              acts_as_tree_set.collect do |item|
                next if item.parent_id && init
                ret += '<li>'
                ret += yield item
                ret += tree_ul( item.children, false, &block ) if item.children.size > 0
                ret += '</li>'
              end
        
              ret += '</ul>'
            end
          end
        
        end
        
        # Example for SchemesViews
        <h3>Rails UL Helper for acts_as_tree</h3>
        <%= tree_ul( @schemes ) { |item| 
                        "#{item.name} [ c r u #{link_to 'd', scheme_path( item ), :confirm => 'Sure?', :method => :delete } ] 
                         #{ link_to 'add document', new_scheme_document_path( item ) if item.children_count.zero? }
                         #{ tell_me_documents( item ) unless item.documents.empty? }" } %>