I got decimal.InvalidOperation: [<class 'decimal.ConversionSyntax'>] - django

Question

views.py
#api_view(["POST", "GET"])
#permission_classes([IsAuthenticated])
def add_order(request, pk):
print(request.user)
customer = md.Customer.objects.get(pk=pk)
if request.method == "POST":
description = request.data['description']
price = request.data['price']
order = md.Order.objects.create(customer=customer,
date_created=zt.now(),
description=description,
price=float(price),
customer_total_when_created=customer.total_owe[0]
)
try:
is_paid = request.data['is_paid']
if is_paid == "on":
who_paid = request.data['who_paid']
payment_method = request.data['payment_method']
who_took_money = request.user
if who_paid == customer.name:
order.who_paid = customer
elif who_paid == customer.parent:
order.who_paid = customer.parent
order.payment_method = payment_method
order.who_took_money = who_took_money
order.date_paid = zt.now()
customer.total = customer.total_owe
customer.save()
order.save()
except:
print("no payment succeed")
order_api = OrderSerializer(order)
return Response(order_api.data)
customer_api = CustomerSerializer(customer)
parent_api = CustomerSerializer(customer.parent)
context = {
"customer": customer_api.data,
"parent":parent_api.data,
"sample": [
{"description": "secreal", "price": "12.21", "is_paid": "on", "who_paid": "azra", "payment_method": "CARD"}
]
}
return Response(context)
models.py
class Order(models.Model):
payment_method_list = [("CASH","CASH"),("CARD","CARD")]
customer = models.ForeignKey(Customer,on_delete=models.CASCADE,null=True,blank=True,)
who_paid = models.ForeignKey(Customer,on_delete=models.CASCADE,null=True,blank=True, related_name='%(class)s_requests_created')
who_took_money = models.ForeignKey(User,on_delete=models.CASCADE,null=True,blank=True, related_name='who_took_money')
payment_method = models.CharField(choices=payment_method_list,max_length=4,default="CASH",blank=True,null=True)
date_paid = models.DateTimeField(blank=True,null=True)
date_created = models.DateTimeField(blank=True, null=True)
date_modified = models.DateTimeField(blank=True, null=True, auto_now=True)
is_paid = models.BooleanField(default=False, blank=True,null=True)
customer_total_when_paid = models.DecimalField(max_digits=5,decimal_places=2,null=True,blank=True)
customer_total_when_created = models.DecimalField(max_digits=5,decimal_places=2,null=True,blank=True)
description = models.TextField(blank=True,null=True)
price = models.DecimalField(max_digits=5,decimal_places=2,null=True,blank=True)
def __str__(self):
return self.description[0:12]
from django.db.models.signals import post_save
def update_total_owe_created_order(sender,instance,created,**kwargs):
if created:
order = instance
customer = order.customer
customer.total = customer.total_owe[0]
customer.save()
post_save.connect(update_total_owe_created_order,sender=Order)
def update_total_owe_updated_order(sender,instance,created,**kwargs):
if created==False:
order = instance
customer = order.customer
customer.total = customer.total_owe[0]
customer.save()
post_save.connect(update_total_owe_updated_order,sender=Order)
I have an app that you send your order to and it adds to database.
It only allows authenticated user to add order; so it shows who added that order. I can get the request.user with JWT authentication but can't save the model. When I send an API post request, I get that error. I could get the user with token but it gives me that error. I don't know why. I am using postman. I didn't get it normally but when I use postman it doesn't work.
ret = super().data
File "C:\Users\homet\Desktop\pharmacy\venv\lib\site-packages\rest_framework\serializers.py", line 253, in data
self._data = self.to_representation(self.instance)
File "C:\Users\homet\Desktop\pharmacy\venv\lib\site-packages\rest_framework\serializers.py", line 522, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "C:\Users\homet\Desktop\pharmacy\venv\lib\site-packages\rest_framework\serializers.py", line 522, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "C:\Users\homet\Desktop\pharmacy\venv\lib\site-packages\rest_framework\fields.py", line 1127, in to_representation
value = decimal.Decimal(str(value).strip())
decimal.InvalidOperation: [<class 'decimal.ConversionSyntax'>]

Answer 1

The price in your Order model is a decimal field but you are casting the price from post request to float while creating the Order object.
price = models.DecimalField(max_digits=5,decimal_places=2,null=True,blank=True)
The price should be a Decimal object instead of float.
order = md.Order.objects.create(customer=customer,
date_created=zt.now(),
description=description,
price=Decimal(price),
customer_total_when_created=customer.total_owe[0]
)
customer_total_when_created should also be a Decimal instance but you haven't posted the Customer model which has total_owe.