模型中的django循环导入
我知道我在这里有一个循环导入，但其中一个用于定义一些外键字段，另一个仅用于另一个模型中的属性。
楷模：
收据/models.py
from django.db import models
from employees.models import Employee
class Receipt(models.Model):
Supervisor = models.ForeignKey(Employee, on_delete=models.CASCADE, related_name='receipt_supervisor')
Employee = models.ForeignKey(Employee, on_delete=models.CASCADE, related_name='receipt_employee')
amount = models.DecimalField(max_digits=6, decimal_places=2)
员工/模型.py
from django.db import models
from receipts.models import Receipt
class Employee(models.Model):
number = models.CharField(max_length=50, unique=True)
first_name = models.CharField(max_length=255)
last_name = models.CharField(max_length=255)
@property
def receipt_sum(self):
receipts = Receipt.objects.filter(Employee=self.pk)
sum = 0
for receipt in receipts:
sum += receipt.amount
return sum
我收到此错误：
无法从部分初始化的模块“employees.models”中导入名称“Employee”（很可能是由于循环导入）
有没有办法解决这个问题，以便我可以在 Employee 属性中进行收据查询？或者我需要在别处做这个计算吗？
谢谢！
回答
有没有办法解决这个问题，以便我可以在
Employee物业中进行收据查询？
是的，您可以在方法中导入模块：
from django.db import models
class Employee(models.Model):
number = models.CharField(max_length=50, unique=True)
first_name = models.CharField(max_length=255)
last_name = models.CharField(max_length=255)
@property
def receipt_sum(self):
from receipts.models import Receipt
receipts = Receipt.objects.filter(Employee=self.pk)
sum = 0
for receipt in receipts:
sum += receipt.amount
return sum但其实完全没有必要导入Receipt，你可以利用receipt_employeerelation来访问相关的Receipt对象，你可以用.aggregate(…)[Django-doc]来汇总数据库端的元素，这样可能效率更高：
from django.db import models
from django.db.models import Sum
class Employee(models.Model):
number = models.CharField(max_length=50, unique=True)
first_name = models.CharField(max_length=255)
last_name = models.CharField(max_length=255)
@property
def receipt_sum(self):
return self.receipt_employee.aggregate(
total=Sum('amount')
)['total'] or 0