django nested serialization of many to many relationship having an intermediate table - django

Question

I have seen a lot of posts on how to deserialize and serialize nested relationships of tables having a many to many relationship, but when an intermediate table is used in a many to many relationship I am not able to achieve deserialization.
This is because an intermediate table requires two foreign keys, one each from the two tables participating in the relation.
I have an Order model and a Service model which are in a many to many relationship via an OrderItem intermediate table.
I need to pass a JSON request like this:
{"service_time":"2015-11-14 10:00:51+0530",
"address":"xyz",
"items":[{"order": "1", "service_id":"4"},
{"order":"1", "service_id":"5"}]
}
The "service_time" and "address" elements get saved in the Order table. Now the problem arises with the "items" JSON array. I pass the "service_id" (foreign key to the Service table) and I need to pass "order" (foreign key to the Order table) too as it is a required field. The problem is that the primary key of the Order table is not known when the request is sent(as the Order is also created as a part of the same request). How can I achieve deserialization in this scenario?
I tried something like this but it didn't work out.
class OrderSerializer(serializers.ModelSerializer):
items = ItemSerializer(many=True)
class Meta:
model = Order
def create(self, validated_data):
items_data = validated_data.pop('items')
orders = Order.objects.create(**validated_data)
for item in items_data:
#order = item['order']
service = item['service']
//Passing the Order object just created as the foreign key of OrderItem
orderItem = OrderItem.objects.create(order=orders, service=service)
orderItem.save()
return orders
class ServiceSerializer(serializers.ModelSerializer):
group = serializers.CharField(source="group.group_name")
category = serializers.IntegerField(source="group.category_id")
class Meta:
model = Service
fields = ['id', 'service_name', 'price', 'special_price', 'service_time', 'group', 'category']
class ItemSerializer(serializers.ModelSerializer):
service_detail = ServiceSerializer(source="service", read_only=True)
class Meta:
model = OrderItem
I get an error saying 'Service' object has no attribute 'order'.
I know the Service model does not have an "order" attribute, but I am creating an OrderItem object, not a Service object.
Any suggestions will be helpful!
Edit: Adding the models used
class Order(models.Model):
STATUSES = [('PENDING', 'Pending'), ('PROCESSING', 'Processing'), ('COMPLETE', 'Complete'), ('CANCELED', 'Canceled')]
PAYMENT_STATUSES = [('PENDING', 'Pending'), ('PAID', 'Paid'),]
CANCEL_REASON = [('NO_SERVICE', 'No Service In Area'), ('NO_STYLIST', 'Stylist Not Available'), ('STYLIST_REFUSED', 'Stylist Refused After Accepting',),
('CUSTOMER_UNREACHABLE', 'Customer Not Reachable'), ('CUSTOMER_CANCELED', 'Customer Canceled at Fisrt Call'), ('CUSTOMER_REFUSED', 'Customer Refused at Last Moment'),
('DUPLICATE_ORDER', 'Duplicate Order'), ('MALE_CLIENT', 'Male Client'), ('CALLCENTER_DELAY', 'Delay/Error at Frontdesk')]
serial = models.CharField(max_length=10, null=True, blank=True,)
customer = models.ForeignKey(Customer, verbose_name="customer", related_name="ordersbycustomer")
stylist = models.ForeignKey(Stylist, null=True, blank=True, verbose_name="stylist", related_name="ordersbystylist")
# TODO, Use timezone.now
service_time = models.DateTimeField(default=timezone.now, blank=True)
started_moving = models.DateTimeField(null=True, blank=True)
service_start_at = models.DateTimeField(null=True, blank=True)
service_end_at = models.DateTimeField(null=True, blank=True)
reached_safely = models.DateTimeField(null=True, blank=True)
sub_total = models.FloatField(default=0)
discounts = models.FloatField(default=0)
grand_total = models.FloatField(default=0)
total_time = models.IntegerField(default=0)
status = models.CharField(max_length=32, choices=STATUSES, default='PENDING')
payment_status = models.CharField(max_length=32, choices=PAYMENT_STATUSES, default='PENDING')
items = models.ManyToManyField(Service, through='OrderItem')
address = models.ForeignKey(Address, null=True, blank=True, related_name='+', on_delete=models.SET_NULL)
amount_received = models.FloatField(default=0)
send_sms = models.BooleanField(default=True)
thru_app = models.BooleanField(default=True)
referral_discount = models.FloatField(default=0)
cancellation_reason = models.CharField(max_length=64, choices=CANCEL_REASON, null=True, blank=True)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
def __unicode__(self):
return self.serial
def _get_service_list(self):
return ','.join(str(p.description) for p in self.items.all())
service_list = property(_get_service_list)
class Service(models.Model):
group = models.ForeignKey(Group, related_name="services")
service_name = models.CharField(max_length=128)
price = models.FloatField(default=0)
special_price = models.FloatField(default=0)
service_time = models.IntegerField()
description = models.CharField(max_length=123)
is_active = models.BooleanField(default=True)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
def __unicode__(self):
return '{} ({})'.format(self.service_name, self.group)
class OrderItem(models.Model):
order = models.ForeignKey(Order)
service = models.ForeignKey(Service)
price = models.FloatField(default=0)
special_price = models.FloatField(default=0)
qty = models.IntegerField(default=1)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
def __unicode__(self):
return self.service.service_name
Edit2: Added the other related serializers.
One important thing I forgot to mention is that, the data gets saved in the DB, but the exception is still raised.