Nested serializer representation for PrimaryKeyRelatedField - python-3.x

Question

I want to add and remove products to an order by only using their ids, but I want the order representation to look like a nested serializer.
My Models:
class Product(models.Model):
title = models.CharField(max_length=200)
price = models.DecimalField(max_digits=1_000, decimal_places=2)
def __str__(self):
return self.title
class Order(models.Model):
date = models.DateField()
products = models.ManyToManyField(Product, blank=True, related_name='orders')
My Serializers:
class ProductSerializer(serializers.ModelSerializer):
price = serializers.DecimalField(max_digits=1_000,
decimal_places=2,
coerce_to_string=False)
class Meta:
model = Product
fields = ['id', 'title', 'price']
class OrderSerializer(serializers.ModelSerializer):
products = serializers.PrimaryKeyRelatedField(queryset=Product.objects.all(), many=True)
class Meta:
model = Order
fields = ['id', 'date', 'products']
I'm trying to get the below representation:
{
"id": 1,
"date": "2021-08-12",
"products": [
{
"id": 1,
"title": "Item 1",
"price": 19.99
},
{
"id": 3,
"title": "Item 3",
"price": 49.99
}
]
}
However, if I want to create the above order the json should look like this:
{
"date": "2021-08-12",
"products":[1, 3]
}
And if I want to add a product with id==2 to the above order it should look like this:
{
"id": 1,
"date": "2021-08-12",
"products":[1, 3, 2]
}
I've tried overriding the to_representation() method and adding a nested serializer there, but I have no idea how to go about it. Should it look something like this, or am I going in a completely wrong direction here?
def to_representation(self, instance):
data = super().to_representation(instance)
data['products'] = ProductSerializer(data=instance['products'])
return data

Answer 1

Ended up fixing it with the to_representation() method. I don't know if this is the best way to do it, but it works for now.
def to_representation(self, instance):
data = super().to_representation(instance)
products_list = []
for product_id in data['products']:
product = instance.products.get(pk=product_id)
products_list.append(
{
'id': product.id,
'title': product.title,
'price': product.price
}
)
data['products'] = products_list
return data

Answer 2

use Nested Serializer Relationships.
and your OrderSerializer serializer class will be like this:
class OrderSerializer(serializers.ModelSerializer):
products = ProductSerializer(many=True)
class Meta:
model = Order
fields = ['id', 'date', 'products']