[Django]-Suggestions for returning relational data in Django REST Framework

if you want to display only a few properties of an item in your ShoppingList you can use the SerializerMethodField method in your serializer

this would work as –

class ShoppingListSerializer(serializers.ModelSerializer):
    itemProperty1 = serializers.SerializerMethodField()
    itemProperty2 = serializers.SerializerMethodField()

    class Meta:
        model = ShoppingList
        fields = ('id', "itemProperty1", "itemProperty2", 'more_fields')
   
    def get_itemProperty1(self, instance):
        return instance.item.anyPropertyOfItem if instance.item else ''

    def get_itemProperty2(self, instance):
        return instance.item.anyPropertyOfItem if instance.item.else ''

anyPropertyOfItem can be anything from item models.
Setting your serializer this way, your ShoppingList view will automatically show 2 new fields.

or you can also define read only fields with the help of @property in models to get the required field.

If you want to display all the properties of the item in the ShoppingList view, you can write here, will edit my answer. There you need to use related_name and get the item serializer in Shoppinglist serializer as the extra field.