I have a question about django.
I have ManyToMany Models here
class Product(models.Model):
name = models.CharField(max_length=255)
price = models.DecimalField(default=0.0, max_digits=9, decimal_places=2)
stock = models.IntegerField(default=0)
def __unicode__(self):
return self.name
class Cart(models.Model):
customer = models.ForeignKey(Customer)
products = models.ManyToManyField(Product, through='TransactionDetail')
t_date = models.DateField(default=datetime.now())
t_sum = models.FloatField(default=0.0)
def __unicode__(self):
return str(self.id)
class TransactionDetail(models.Model):
product = models.ForeignKey(Product)
cart = models.ForeignKey(Cart)
amount = models.IntegerField(default=0)
For 1 cart object created, I can insert as many as new TransactionDetail object (the product and amount). My question is. How can I implement the trigger? What I want is whenever a Transaction detail is created, I want the amount of the product's stock is substracted by the amount in the transactiondetail.
I've read about post_save() but I'm not sure how to implement it. maybe something like this
when:
post_save(TransactionDetail,
Cart) #Cart object where TransactionDetail.cart= Cart.id
Cart.stock -= TransactionDetail.amount
If you really want to use signals to achieve this, here's briefly how,
from django.db.models.signals import post_save
from django.dispatch import receiver
class TransactionDetail(models.Model):
product = models.ForeignKey(Product)
# method for updating
@receiver(post_save, sender=TransactionDetail, dispatch_uid="update_stock_count")
def update_stock(sender, instance, **kwargs):
instance.product.stock -= instance.amount
instance.product.save()