title: Django REST Framework: define fields in nested object?
body: <p>I got events that happen at locations:</p>
  
  <pre><code>class Event(models.Model):
      title = models.CharField(max_length=200)
      date_published = models.DateTimeField('published date',default=datetime.now, blank=True)
      date_start = models.DateTimeField('start date')
      date_end = models.DateTimeField('end date')
      def __unicode__(self):
          return self.title
      description = models.TextField()
      price = models.IntegerField(null=True, blank=True)
      tags = TaggableManager()
      location = models.ForeignKey(Location, blank=False)
  
  class Location(models.Model):
      location_title = models.CharField(max_length=200)
      location_date_published = models.DateTimeField('published date',default=datetime.now, blank=True)
      location_latitude = models.CharField(max_length=200)
      location_longitude = models.CharField(max_length=200)
      location_address = models.CharField(max_length=200)
      location_city = models.CharField(max_length=200)
      location_zipcode = models.CharField(max_length=200)
      location_state = models.CharField(max_length=200)
      location_country = models.CharField(max_length=200)
      location_description = models.TextField()
      def __unicode__(self):
          return u'%s' % (self.location_title)
  </code></pre>
  
  <p>I can get the results of all via:</p>
  
  <pre><code>class EventSerializer(serializers.HyperlinkedModelSerializer):
      id = serializers.Field()
      class Meta:
          model = Event
          depth = 2
          fields = ('url','id','title','date_start','date_end','description', 'price', 'location')
  </code></pre>
  
  <p>Which outputs:</p>
  
  <pre><code> {
              "url": "http://localhost:8000/api/event/3/", 
              "id": 3, 
              "title": "Testing", 
              "date_start": "2013-03-10T20:19:00Z", 
              "date_end": "2013-03-10T20:19:00Z", 
              "description": "fgdgdfg", 
              "price": 10, 
              "location": {
                  "id": 2, 
                  "location_title": "Mighty", 
                  "location_date_published": "2013-03-10T20:16:00Z", 
                  "location_latitude": "37.767475", 
                  "location_longitude": "-122.406878", 
                  "location_address": "119 Utah St, San Francisco, CA 94103, USA", 
                  "location_city": "San Francisco", 
                  "location_zipcode": "94103", 
                  "location_state": "California", 
                  "location_country": "United States", 
                  "location_description": "Some place"
              }
          }, 
  </code></pre>
  
  <p>However, I don't want it to grab all fields, as I don't need all of them. How can I define what fields should be retrieved from my nested object? Thanks!</p>