Question

这是我的第一个模特

from django.db import models
from django.contrib.auth.models import User

CHOICES = (('Earned Leave','Earned Leave'),('Casual Leave','Casual Leave'),('Sick Leave','Sick Leave'),('Paid Leave','Paid Leave'))
STATUS_CHOICES = (('0', 'Rejected'),('1', 'Accepted'),)


class Leave(models.Model):

    employee_ID = models.CharField(max_length = 20)
    name = models.CharField(max_length = 50)
    user = models.ForeignKey(User, on_delete = models.CASCADE, null =True)
    type_of_leave = models.CharField(max_length = 15, choices = CHOICES)
    from_date = models.DateField()
    to_date = models.DateField()
    status = models.CharField(max_length = 15, choices = STATUS_CHOICES)

    @property
    def date_diff(self):
        return (self.to_date - self.from_date).days

这是我的第二个模特

class History(models.Model):

    first_name = models.CharField(max_length = 50)
    last_name = models.CharField(max_length = 50)
    employee_ID = models.CharField(max_length = 20)
    earned_leave = models.IntegerField()
    casual_leave = models.IntegerField()
    sick_leave = models.IntegerField()
    paid_leave =models.IntegerField()

在保存第一个模型Leave之后，我写了重写

之类的保存方法。

def save(self, *args, **kwargs):
        super(Leave, self).save()
        if  self.employee_ID == History.employee_ID:
            if self.status == '1':
                if self.type_of_leave == 'Earned Leave':

                    history = History.objects.update(
                earned_leave = self.date_diff,  
                )

但是在保存第一个模型后，“历史记录”模型中的所有条目都将更新。每个用户在历史记录表中都有一个单独的条目，其中包含用户的详细信息（first_name, last_name, employee_ID），其余用户的默认值为10。保存Leave模型后，仅应与employee_ID模型中与Leave模型的History关联的条目进行更新。为此，我给出为if self.employee_ID == History.employee_ID:，但它不起作用。

我甚至尝试过-

def save(self, *args, **kwargs):
            super(Leave, self).save()
            if  self.employee_ID == History.employee_ID:
                if self.status == '1':
                    if self.type_of_leave == 'Earned Leave':

                        history = History.objects.update(
                    earned_leave = History.earned_leave - self.date_diff,  
                    )

但这不起作用，什么也没有更新，并且出现错误unsupported operand types

因此，该项目的基础是员工离职管理。当用户申请请假并被接受时，剩余天数应在“历史记录”表或模型中得到更新。

如果有其他方法，请共享。

Answer 1

History.objects.update(...)实际上确实更新了所有History对象。您应该在查询中指定要更新的内容：

from django.db.models import F

def save(self, *args, **kwargs):
    super(Leave, self).save()
    if self.status == '1':
        if self.type_of_leave == 'Earned Leave':
            history = History.objects.filter(employee_id=self.employee_id).update(
                earned_leave = F('earned_leave') - self.date_diff,  
            )

此处的F()表达式是指列的值，将由数据库而不是Python计算。

Django：通过覆盖保存方法更新模型

1 个答案: