Item
  has_many :half_links
  belongs_to: category

Category
  has_many :items

HalfLinks
  belongs_to :other_item, :class_name => "Item", :foreign_key => :other_item

<table>
<tr>
  <td>item_id, cat_id</td>
  <td>Item name</td>
  <td>Item Category</td>
  <td>Pic</td>
</tr>
<% @itemhl.each do |hl| %>
<tr>
    <td><%= hl.other_item_id %> <%= hl.other_category_id %></td>
    <td><%= link_to hl.other_item.name, item_path(hl.other_item) %></td>
    <td><%= link_to hl.other_item.category.name, category_path(hl.other_item.category) %></td>
    <td><%= image_tag hl.other_item.itemimage.url(:thumb) %></td>
</tr>
<% end %>
 </table>
</p>

@itemhlc = @itemhl.map{|c| c.other_item.category.name }.uniq