Adding data to multiple tables using django rest serializers - reactjs

Question

I am working on django rest framework coupled with react frontend. I am building a simple web service for a medium-sized organisation.
Here is my Invoice model from models.py
class Invoice(models.Model):
invoice_id = models.AutoField(primary_key=True, editable=False)
customer = models.ForeignKey(Customer, on_delete=models.CASCADE)
date = models.DateField(auto_now_add=True)
builty_num = models.CharField(max_length=100)
total_amount = models.FloatField(validators=[MinValueValidator(0.0)])
class Meta:
ordering = ['date', 'customer']
InvoiceDetail from models.py
class InvoiceDetail(models.Model):
invoice = models.ForeignKey(Invoice, on_delete=models.CASCADE)
product = models.ForeignKey(Product, on_delete=models.SET_NULL, null=True)
warehouse = models.ForeignKey(Warehouse, on_delete=models.SET_NULL, null=True)
rate = models.FloatField(validators=[MinValueValidator(0.0)])
num_thaan = models.PositiveIntegerField()
gazaana_per_thaan = models.FloatField(validators=[MinValueValidator(0.0)])
Ledger model
class Ledger(models.Model):
TYPE = (
('D','Debit'),
('C','Credit'),
)
customer = models.ForeignKey(Customer, on_delete=models.CASCADE)
date = models.DateField(auto_now_add=True)
detail = models.TextField()
transaction_type = models.CharField(max_length=1, choices=TYPE)
amount = models.FloatField(validators=[MinValueValidator(0.0)])
Now I will be having a form on my front-end which will be sending customer_id and an array of InvoiceDetail which I want to fill my database with. So, I will be using information from that form and use it to fill up multiple entries in my InvoiceDetail and the total_amount would also be calculated from the invoice detail. After this, I would also fill up the ledger based on
the total_amount. Right now, I am unable to figure out a way to do this as I am just able to manipulate a single table via a viewset
P.S. I am using these serializers right now with DefaultRouter()
class CustomerSerializer(serializers.ModelSerializer):
class Meta:
model = Customer
fields = '__all__'
class ProductSerializer(serializers.ModelSerializer):
class Meta:
model = Product
fields = '__all__'
class WarehouseSerializer(serializers.ModelSerializer):
class Meta:
model = Warehouse
fields = '__all__'
class ExpenseSerializer(serializers.ModelSerializer):
class Meta:
model = Expense
fields = '__all__'
class InvoiceSerialiser(serializers.ModelSerializer):
class Meta:
model = Invoice
fields = '__all__'
And this is my views.py
class CustomerViewSet(viewsets.ModelViewSet):
serializer_class = CustomerSerializer
queryset = Customer.objects.all()
class ProductViewSet(viewsets.ModelViewSet):
serializer_class = ProductSerializer
queryset = Product.objects.all()
class WarehouseViewSet(viewsets.ModelViewSet):
serializer_class = WarehouseSerializer
queryset = Warehouse.objects.all()
class ExpenseViewSet(viewsets.ModelViewSet):
serializer_class = ExpenseSerializer
queryset = Expense.objects.all()

Answer 1

In Django REST Framework (DRF), by using Nested Relationships of Serializer Relations data can be added to multiple tables having relationships.
In Nested Relationships, the referred entity can be embedded or nested in the representation of the object that refers to it. Such nested relationships can be expressed by using serializers as fields. If we want to support write-operations to a nested serializer field we need to have create() and/or update() methods in order to explicitly specify how the child relationships should be saved. It may be noted that by default nested serializers are read-only.
Below is the implementation of the relationship between Invoice and InvoiceDetail.
class InvoiceDetailSerialiser(serializers.ModelSerializer):
class Meta:
model = InvoiceDetail
fields = "__all__"
read_only_fields = ("invoice", )
It is required to make invoice readonly in InvoiceDetailSerialiser.
class InvoiceSerialiser(serializers.ModelSerializer):
invoice_details = InvoiceDetailSerialiser(many=True)
class Meta:
model = Invoice
fields = ('invoice_id', 'customer', 'date', 'builty_num', 'total_amount', 'invoice_details')
def create(self, validated_data):
invoice_details_data = validated_data.pop('invoice_details')
invoice= Invoice.objects.create(**validated_data)
for invoice_detail_data in invoice_details_data :
InvoiceDetail.objects.create(invoice=invoice, **invoice_detail_data )
return invoice
If the field is used to represent a to-many relationship, we should add the many=True flag to the serializer field.
Based on the above explanation, rest of the implementations can be developed.
More details on this topic from the official guide can be found here.