title: django serialize make a custom display format
body: <p>This is My code :</p>
  
  <pre><code>for i in Showtime.objects.filter(movie_id=movieid,theater_id=theaterid,movietime__gte=get_today()):
      if i.mvtype not in movietimes:
          movietimes[i.mvtype] = []
      movietimes[i.mvtype].append({i.movietime.strftime('%Y-%m-%d') : i.movietime.strftime('%Y-%m-%dT%H:%M:%S.%fZ')})
  </code></pre>
  
  <p>And the result is :</p>
  
  <pre><code>"3D": [ 
      {
          "2015-01-29": "2015-01-29T01:20:00.000000Z"
      }, 
      {
          "2015-01-29": "2015-01-29T03:10:00.000000Z"
      }, 
      {
          "2015-01-29": "2015-01-29T05:10:00.000000Z"
      }, 
  
      {
          "2015-01-28": "2015-01-28T17:10:00.000000Z"
      }, 
      {
          "2015-01-28": "2015-01-28T01:20:00.000000Z"
      }, 
  ]
  </code></pre>
  
  <p>But what I want like : </p>
  
  <pre><code>"3D": [ 
      {
          "2015-01-29": {
                      "2015-01-29T01:20:00.000000Z",
                      "2015-01-29T03:10:00.000000Z"
                      "2015-01-29T05:10:00.000000Z"
          }, 
  
          "2015-01-28": {
                      "2015-01-28T17:10:00.000000Z"
                      "2015-01-28T01:20:00.000000Z"
          }, 
      }   
  ]    
  </code></pre>
  
  <p>How can I do this , 
  Please help me</p>