title: Django REST get category list with their products list
body: <p>I have two django model named Category and Product. In Category model has "is_featured" boolean field. I need category list in JSON format where is_featured=true and the list of products. The models are like following.</p>
  
  <pre><code>from django.db import models
  
      class Category(models.Model):
          name=models.CharField(max_length=25, blank=False, null=False)
          is_featured=models.BooleanField(default=False)
          parent=models.ForeignKey('self', on_delete=models.CASCADE)
  
          def __str__(self):
              return self.name
  
      class Product(models.Model):
          name=models.CharField(max_length=25, blank=False, null=False)
          category=models.ForeignKey(Category, on_delete=models.CASCADE)
          uom=models.CharField(max_length=10)
          price=models.FloatField()
  
          def __str__(self):
              return '%s %s %s %s' % (self.name, self.category.name, self.price, self.uom)
  </code></pre>
  
  <p>My expected category list (is_featured=true) result will be look like following.</p>
  
  <pre><code>{  
    "id":1,
    "name":"Foods",
    "products":[  
       {  
          "id":2,
          "name":"Chicken Fri",
          "price":80
       },
       {  
          "id":4,
          "name":"Tomato Salad",
          "price":20
       }
    ]
  },
  {  
    "id":3,
    "name":"Vegitable",
    "products":[  
       {  
          "id":3,
          "name":"Potato",
          "price":20
       },
       {  
          "id":6,
          "name":"Bean",
          "price":55
       }
    ]
  }
  </code></pre>
  
  <p>I am beginner in django. Thanks in advance for help. </p>