How can I send the Name of the Item instead of PK in Django-Rest-Framework using POSTMAN? - django-models

Question

So I am creating a E-Commerce API using the Django Rest Framework and I have been trying to send the name of the Item instead of the PK of the Item to create an order.
These are the models I am using:
class Product(models.Model):
product_tag = models.CharField(max_length=10)
name = models.CharField(max_length=100)
description = models.CharField(max_length=500, null=True, blank=True)
category = models.ForeignKey(Category, on_delete=models.CASCADE)
price = models.IntegerField()
stock = models.IntegerField()
image = models.ImageField(default="default.png")
in_stock = models.BooleanField(default=True)
date_created = models.DateField(auto_now_add=True)
class Meta:
ordering = ["-date_created"]
def __str__(self):
return self.name
class PlacedOrder(models.Model):
ordered_by = models.ForeignKey(User, on_delete=models.CASCADE)
first_name = models.CharField(max_length=100)
last_name = models.CharField(max_length=100)
phone = models.CharField(max_length=15)
address = models.CharField(max_length=100)
zipcode = models.CharField(max_length=100)
items = models.ManyToManyField(Product)
total_price = models.IntegerField()
created_at = models.DateTimeField(auto_now_add=True)
class Meta:
ordering = ["-created_at"]
def __str__(self):
return f"{self.ordered_by}"
This is my serializer that I am working with to create an order:
class PlacedOrderSerializer(serializers.ModelSerializer):
ordered_by = serializers.ReadOnlyField(source="ordered_by.email")
class Meta:
model = PlacedOrder
fields = (
"id",
"created_at",
"ordered_by",
"first_name",
"last_name",
"phone",
"address",
"zipcode",
"items",
"total_price",
)
Here is the view I am using to create an order:
class CreateOrder(generics.ListCreateAPIView):
permission_classes = [IsAuthenticated]
queryset = PlacedOrder.objects.all()
serializer_class = PlacedOrderSerializer
def perform_create(self, serializer):
serializer.save(ordered_by=self.request.user)
This is my input in POSTMAN:
{
"first_name": "yes",
"last_name": "no",
"phone": "0100000000",
"address": "whatever address",
"zipcode": "254",
"items": [
1,
1,
2
],
"total_price": "69"
}
and this is the output:
{
"id": 13,
"created_at": "2022-10-26T20:56:08.789574Z",
"ordered_by": "bal#bal.com",
"first_name": "yes",
"last_name": "no",
"phone": "0100000000",
"address": "whatever address",
"zipcode": "254",
"items": [
1,
2
],
"total_price": 69
}
I basically want it to take the name and quantity of the items instead of the PK of the product in the input.
I have tried using RelatedField but that makes it so that "items" just goes null to the backend without taking any products and makes a blank order.

Answer 1

Try this approach:
class PlacedOrderSerializer(serializers.ModelSerializer):
# HERE
ordered_by = serializers.StringRelatedField(many=True, read_only=True)
class Meta:
model = PlacedOrder
fields = (
"id",
"created_at",
"ordered_by",
"first_name",
"last_name",
"phone",
"address",
"zipcode",
"items",
"total_price",
)
But make sure to add self.name to the models __str__.

Answer 2

You need to use a SlugRelatedField [DRF-doc] here, like:
class PlacedOrderSerializer(serializers.ModelSerializer):
ordered_by = serializers.ReadOnlyField(source="ordered_by.email")
items = serializers.SlugRelatedField(
many=True,
slug_field='name',
queryset=Product.objects
)
class Meta:
model = PlacedOrder
fields = (
# ...
)
This will thus make the serializer interpret the name fields, and query the Product objects with that name, and add these to the many-to-many relation.
Note that this will result in a query for each item, so if the list of items can be long, you might want to consider a different strategy, like serializing a list of product PKs, and then in the view construct a mapping name -> product, and use that to construct the many-to-many relation.
Note: It is normally better to use a slug field (a short identifier), than a name field for these kinds of relations. Slugs are meant to be database friendly (only contain ascii characters, no spaces, etc), and furthermore slugs normally do not change, whilst a name can. So if you later rename a Product, then the order will no longer point to the correct product.