title: Group concat using django ORM
body: <p>I need to fire following query using ORM</p>
  <pre><code>SELECT GROUP_CONCAT( af.name ) AS item, ac.name AS categories
  FROM admin_fooditem af
  JOIN admin_category ac ON ( ac.id = af.category_id ) 
  GROUP BY ac.id
  </code></pre>
  <p>The output is as below</p>
  <pre><code>item                              Categories
  
  Tuborg beer                       Beverages
  Mutter Paneer,Palak Paneer        Vegeterian entries
  Coke,Fanta                        Soft drinks
  </code></pre>
  <p>The original tables are</p>
  <p>admin_category</p>
  <pre><code>        id  name    
          11  Softdrinks
          5   Vegeterian Entry
          2   Beverages
  </code></pre>
  <p>admin_fooditem</p>
  <pre><code>        id  name         category_id
          1   Palak Paneer    5
          2   Mutter Paneer   5
          5   Tuborg beer     2
          6   Coke            11
          7   Fanta           11 
  </code></pre>
  <p>I have used simple join <code>query(FoodItem.objects.select_related('Category').all())</code> and then <code>regroup</code> tag in template , but now I need json output of the above sql, I am  clueless so I am using raw sql for now</p>
  <p>Thanks!</p>