Filter with field has relationship in Django?
I have these models in Django:
class Customer(models.Model):
def __unicode__(self):
return self.name
name = models.CharField(max_length=200)
class Sale(models.Model):
def __unicode__(self):
return "Sale %s (%i)" % (self.type, self.id)
customer = models.ForeignKey(Customer)
total = models.DecimalField(max_digits=15, decimal_places=3)
notes = models.TextField(blank=True, null=True)
class Unitary_Sale(models.Model):
book = models.ForeignKey(Book)
quantity = models.IntegerField()
unit_price = models.DecimalField(max_digits=15, decimal_places=3)
sale = models.ForeignKey(Sale)
How can I filter to get all books that customer sale?
I tried:
units=Unitary_Sale.objects.all()
>>> units=Unitary_Sale.objects.all()
>>> for unit in units:
... print unit.sale.customer
... print unit.book,unit.sale.total
...
Sok nara
Khmer Empire (H001) 38.4
Sok nara
killing field (H001) 16
San ta
khmer krom (H001) 20
San ta
Khmer Empire (H001) 20
>>>
what I want:
sok nora:56.4 (38.4+18)
san ta:40 (开发者_高级运维20+20)
Or to dictionary:
{sok nora:156.4, san ta:40}
>>> store_resulte = {}
>>> for unit in units:
... store_resulte[unit.sale.customer] = unit.sale.total
...
>>> print store_resulte
{<Customer: Sok nara>: Decimal("16"), <Customer: san ta>: Decimal("20")}
It should be:
{<Customer: Sok nara>: Decimal("56.4"), <Customer: san ta>: Decimal("40")}
Have a look at aggregation documentation.
I believe this should do the trick (only with version 1.1 or dev.):
Customer.objects.annotate(total=Sum('sale__total'))
EDIT: You can also define a custom method for the class:
class Customer(models.Model):
def __unicode__(self):
return self.name
name = models.CharField(max_length=200)
def total_sale(self):
total = 0
for s in self.sale_set:
total += s.total
return total
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