Django Rest Framework CRUD operations, Serializing Many To Many table and bulk update

Django Rest Framework CRUD operations

Serializing Many To Many Relationship table

api/models.py

 
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from django.db import models
​
​
class Material(models.Model):
    name = models.CharField(max_length=120)
    price = models.FloatField()
​
    def __str__(self):
        return self.name
​
class Product(models.Model):
    name = models.CharField(max_length=120)
    materials = models.ManyToManyField(Material, through='MaterialProduct')
​
    def __str__(self):
        return self.name
​
class MaterialProduct(models.Model):
    """ many to many intermediate table """
    material = models.ForeignKey(Material, on_delete=models.CASCADE)
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    material_ratio = models.FloatField()
​

• Apply models to the database:

  • python manage.py makemigrations
  • python manage.py migrate

---

api/serializers.py

 
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from rest_framework import serializers
from .models import Product, Material, MaterialProduct
​
class MaterialSerializer(serializers.ModelSerializer):
    class Meta:
        model = Material
        fields = '__all__'
​
class MaterialProductSerializer(serializers.ModelSerializer):
    material = MaterialSerializer()
​
    class Meta:
        model = MaterialProduct
        fields = '__all__'
​
class ProductSerializer(serializers.ModelSerializer):
    # To get materials which are associated with a product
    materials = serializers.SerializerMethodField()
​
    class Meta:
        model = Product
        fields = '__all__'
        depth = 1
​
    def get_materials(self, obj):
        query_set = MaterialProduct.objects.filter(product=obj)
        return [MaterialProductSerializer(item).data for item in query_set]
​

---

api/routes.py

 
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from rest_framework.views import APIView
from rest_framework.response import Response
​
from polls.serializers import MaterialSerializer, ProductSerializer, MaterialProductSerializer
from polls.models import Product, Material, MaterialProduct
​
​
class ProductList(APIView):
    def get(self, request):
        products = Product.objects.all()
        serializer = ProductSerializer(products, many=True)
        return Response(serializer.data)
​

api/urls.py

 
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from django.urls import path
from polls.routes import ProductList
​
​
urlpatterns = [
    path('api/products', ProductList.as_view(), name='products'),
​
]
​

project/urls.py

 
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from django.contrib import admin
from django.urls import path, include
​
urlpatterns = [
    path('admin/', admin.site.urls),
    path('',include('api.urls')),
]
​

• GET request to http://127.0.0.1:8000/api/products
• Returned data:

 
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[
    {
        "id": 1,
        "materials": [
            {
                "id": 1,
                "material": {
                    "id": 3,
                    "name": "material3",
                    "price": 15.0
                },
                "material_ratio": 20.0,
                "product": 1
            },
            {
                "id": 2,
                "material": {
                    "id": 6,
                    "name": "material6",
                    "price": 30.0
                },
                "material_ratio": 80.0,
                "product": 1
            }
        ],
        "name": "product44"
    },
    {
        "id": 2,
        "materials": [],
        "name": "product66"
    },
    {
        "id": 3,
        "materials": [
            {
                "id": 6,
                "material": {
                    "id": 1,
                    "name": "material1",
                    "price": 5.0
                },
                "material_ratio": 5.0,
                "product": 3
            },
            {
                "id": 7,
                "material": {
                    "id": 2,
                    "name": "material2",
                    "price": 10.0
                },
                "material_ratio": 15.0,
                "product": 3
            },
            {
                "id": 8,
                "material": {
                    "id": 4,
                    "name": "material4",
                    "price": 20.0
                },
                "material_ratio": 25.0,
                "product": 3
            },
            {
                "id": 9,
                "material": {
                    "id": 8,
                    "name": "material8",
                    "price": 50.0
                },
                "material_ratio": 45.0,
                "product": 3
            },
            {
                "id": 10,
                "material": {
                    "id": 10,
                    "name": "material10",
                    "price": 1000.0
                },
                "material_ratio": 10.0,
                "product": 3
            }
        ],
        "name": "product100"
    },
    {
        "id": 4,
        "materials": [],
        "name": "product200"
    },
    {
        "id": 5,
        "materials": [
            {
                "id": 3,
                "material": {
                    "id": 2,
                    "name": "material2",
                    "price": 10.0
                },
                "material_ratio": 30.0,
                "product": 5
            },
            {
                "id": 4,
                "material": {
                    "id": 4,
                    "name": "material4",
                    "price": 20.0
                },
                "material_ratio": 40.0,
                "product": 5
            },
            {
                "id": 5,
                "material": {
                    "id": 8,
                    "name": "material8",
                    "price": 50.0
                },
                "material_ratio": 30.0,
                "product": 5
            }
        ],
        "name": "product300"
    },
    {
        "id": 6,
        "materials": [
            {
                "id": 11,
                "material": {
                    "id": 5,
                    "name": "material5",
                    "price": 25.0
                },
                "material_ratio": 100.0,
                "product": 6
            }
        ],
        "name": "product444"
    }
]
​
​
​

Product Detail

api/routes.py

 
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...
from django.shortcuts import get_object_or_404
class ProductDetail(APIView):
    def get(self, request, pk):
        product = get_object_or_404(Product, pk=pk)
        serializer = ProductSerializer(product)
        return Response(serializer.data)
​

api/urls.py

 
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from polls.routes import ProductList, ProductDetail
​
path('api/products/<int:pk>', ProductDetail.as_view(), name='product-detail'),

• GET request to the http://127.0.0.1:8000/api/products/5
• Returned data:

 
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{
    "id": 5,
    "materials": [
        {
            "id": 3,
            "material": {
                "id": 2,
                "name": "material2",
                "price": 10.0
            },
            "material_ratio": 30.0,
            "product": 5
        },
        {
            "id": 4,
            "material": {
                "id": 4,
                "name": "material4",
                "price": 20.0
            },
            "material_ratio": 40.0,
            "product": 5
        },
        {
            "id": 5,
            "material": {
                "id": 8,
                "name": "material8",
                "price": 50.0
            },
            "material_ratio": 30.0,
            "product": 5
        }
    ],
    "name": "product300"
}
​

Create Product | POST request

api/routes.py

 
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from rest_framework import status
​
class ProductList(APIView):
    def get(self, request):
        #...
​
     def post(self, request, format=None):
        serializer = ProductSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
​

• POST request to the http://127.0.0.1:8000/api/products
• data : {"id":integer_number, "name":"new product"}
• returned data:

 
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{
    "id": 7,
    "materials": [],
    "name": "new_product"
}

Update Product | PUT request

api/routes.py

 
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class ProductDetail(APIView):
    def get(self, request, pk):
        #...
        
    def put(self, request, pk, format=None):
        product = get_object_or_404(Product, pk=pk)
        serializer = ProductSerializer(product, data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

• PUT request to the http://127.0.0.1:8000/api/products/6
• data: {"name":"product444updated"}
• returned data:

 
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{
    "id": 6,
    "materials": [
        {
            "id": 11,
            "material": {
                "id": 5,
                "name": "material5",
                "price": 25.0
            },
            "material_ratio": 100.0,
            "product": 6
        }
    ],
    "name": "product444updated"
}

Delete Request

api/routes.py

 
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​
class ProductDetail(APIView):
    def get(self, request, pk):
        #...
​
    def put(self, request, pk, format=None):
        #...
​
    def delete(self, request, pk, format=None):
        product = get_object_or_404(Product, pk=pk)
        product.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)
​

• DELETE request : curl -X DELETE http://127.0.0.1:8000/api/products/6

Product Material List

api/routes.py

 
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class ProductList(APIView):
    #...
​
class ProductDetail(APIView):
    #...
​
class ProductMaterialList(APIView):
​
    def get(self, request, pk):
        mp = MaterialProduct.objects.filter(product=pk)
        materials = []
        for item in mp:
            materials.append(item.material)
        serializer = MaterialSerializer(materials, many=True)
        return Response(serializer.data)

api/urls.py

 
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from api.routes import ProductList, ProductDetail, ProductMaterialList
​
urlpattern = [
    path('api/products', ProductList.as_view(), name='products'),
    path('api/products/<int:pk>', ProductDetail.as_view(), name='product-detail'),
     path('api/products/<int:pk>/materials', ProductMaterialList.as_view(), name='product-material-list'),
]

• GET request to the http://127.0.0.1:8000/api/products/1/materials -returned data:

 
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[
    {
        "id": 3,
        "name": "material3",
        "price": 15.0
    },
    {
        "id": 6,
        "name": "material6",
        "price": 30.0
    }
]
​

Product's multiple Material Update | bulk update

api/serializers.py

 
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​
class MaterialListSerializer(serializers.ListSerializer):
    def update(self, instance, validated_data):
        material_mapping = {material.id: material for material in instance}
        data_mapping = {item['id']: item for item in validated_data}
​
        result = []
        for material_id, data in data_mapping.items():
            material = material_mapping.get(material_id, None)
            if material is not None:
                result.append(self.child.update(material, data))
        return result
    
​
​
class MaterialSerializer(serializers.ModelSerializer):
    id = serializers.IntegerField()
​
    class Meta:
        model = Material
        fields = '__all__'
        list_serializer_class = MaterialListSerializer
​

api/routes.py

 
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​
class ProductMaterialList(APIView):
​
    def get(self, request, pk):
        #...
    def put(self, request, pk, format=None):
        mp = MaterialProduct.objects.filter(product=pk)
        materials = []
        for item in mp:
            materials.append(item.material)
        serializer = MaterialSerializer(materials, request.data, many=True)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
​

• PUT request to the http://127.0.0.1:8000/api/products/1/materials
• data :

 
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[ 
{"id" : 3,  "name" : "material3_UPDATED" , "price" : 200 }, 
{"id" : 6 ,  "name" : "material6_UPDATED",  "price" : 600  }
]

• returned_data:

 
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[
    {
        "id": 3,
        "name": "material3_UPDATED",
        "price": 200.0
    },
    {
        "id": 6,
        "name": "material6_UPDATED",
        "price": 600.0
    }
]
​