Nsryjdtyk

when I am implementing this code-example on the documentation (I had to implement the create method myself because I have nested objects and inserting them is not supported by default)

def create(self, validated_data):

    profile_data = validated_data.pop('profile')

    user = User.objects.create(**validated_data)

    Profile.objects.create(user=user, **profile_data)

    return user

https://www.django-rest-framework.org/api-guide/serializers/#writing-create-methods-for-nested-representations

I'm getting this error

create() argument after ** must be a mapping, not list

My implementation of the example on my project is the following :

def create(self, validated_data):

    product_data = validated_data.pop('categories')

    product = Product.objects.create(**validated_data)

    Product.objects.create(product=product, **product_data)

    return product

the whole serializers.py file

from rest_framework import serializers

from products_and_categories.models import Product, Category

from django.db import models





class CategorySerializer(serializers.ModelSerializer):

    def to_representation(self, obj):

        if 'categories' not in self.fields:

            self.fields['categories'] = CategorySerializer(obj, many=True)      

        return super(CategorySerializer, self).to_representation(obj)



    class Meta:

        model = Category

        fields = ("name", 'products', 'categories')



class ProductSerializer(serializers.ModelSerializer):

    categories = CategorySerializer(many=True)

    class Meta:

        model = Product

        fields = ("product_code", "name", "quantity", "price", 'categories')



    def create(self, validated_data):

        product_data = validated_data.pop('categories')

        product = Product.objects.create(**validated_data)

        Product.objects.create(product=product, **product_data)

        return product

my models.py file:

from django.db import models



# Create your models here.



class Category(models.Model):

    name = models.CharField(max_length=255)

    categoriesId = models.ForeignKey('self', related_name='categories',on_delete=models.CASCADE, blank=True, null=True)



class Product(models.Model):

    product_code = models.CharField(max_length=255)

    name = models.CharField(max_length=255)

    price = models.IntegerField()

    quantity = models.IntegerField()

    categories = models.ManyToManyField(Category, related_name='products')

can anybody help me figure out what's wrong ?

You're confusing various names here. You pop the categories element from validated_data, and assign it to product_data; but it is not product data, it is a list of categories.

You then try and create a Product with that data related to an existing product - presumably you meant to create a Category there. But again what you have is a list, so you need to iterate through and create one category per entry.

And finally note that you have a many-to-many relationship between product and category, not a foreign key as in the example, so you can't use that product=product syntax.

This would be better as:

def create(self, validated_data):

    category_data = validated_data.pop('categories')

    product = Product.objects.create(**validated_data)

    for category in category_data:

        product.categories.create(**category)

    return product

(Although note that yes, creating nested items is supported by DRF; see the docs on serializer relations.)