django REST framework - limited queryset for nested ModelSerializer?

Question

I have a ModelSerializer, but by default it serializes all the objects in my model. I would like to limit this queryset to only the most recent 500 (as opposed to all 50 million). How do I do this?

What I have currently is the following:

class MyModelSerializer(serializers.ModelSerializer):     class Meta:         model = MyModel 

The reason I don't think I can just specify the queryset in my viewset is that this is in fact the nested portion of another serializer.

models.py

class Container(models.Model):     size  = models.CharField(max_length=20)     shape = models.CharField(max_length=20)  class Item(models.Model):     container = models.ForeignKey(Container, related_name='items')     name  = models.CharField(max_length=20)     color = models.CharField(max_length=20) 

views.py

class ContainerViewSet(viewsets.ModelViewSet):     queryset = Container.objects.all()  # only a handful of containers     serializer_class = ContainerSerializer 

serializers.py

class ItemSerializer(serializers.ModelSerializer):     class Meta:         model = Item         fields = ('name', 'color')  class ContainerSerializer(serializers.ModelSerializer):     items = ItemSerializer(many=True)  # millions of items per container     class Meta:         model = Container         fields = ('size', 'shape', 'items') 

Answer 1

In your View Set you may specify the queryset like follows:

from rest_framework import serializers, viewsets  class MyModelSerializer(serializers.ModelSerializer):     class Meta:         model = MyModel  class MyModelViewSet(viewsets.ModelViewSet):     queryset = MyModel.objects.all()[:500]     serializer_class = MyModelSerializer 

I think what you are looking for is the SerializerMethodField.

So your code would look as follows:

class ContainerSerializer(serializers.ModelSerializer):     items = SerializerMethodField('get_items')      class Meta:         model = Container         fields = ('size', 'shape', 'items')      def get_items(self, container):         items = Item.objects.filter(container=container)[:500]  # Whatever your query may be         serializer = ItemSerializer(instance=items, many=True)         return serializer.data 

The one catch is that the SerializerMethodField is read only.