Question

我有信号功能：

@receiver(post_save, sender=Task)
def my_handler():
    executor = User.objects.filter(user_type='Executer')
    executor.balance += Task.money
    executor.save()

我的功能应该在添加任务后为执行者添加资金。但它给出了错误：

Internal Server Error: /api/v1/tasks/
Traceback (most recent call last):
  ...
  File "/home/k/pro/freelance-django/free/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 1853, in get_prep_value
    return int(value)
ValueError: invalid literal for int() with base 10: 'Executer'
[20/Sep/2017 14:00:30] "POST /api/v1/tasks/ HTTP/1.1" 500 188088

用户类如下所示：

   from __future__ import unicode_literals

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


class User(AbstractUser):
    CUSTOMER = 1
    EXECUTER = 2

    USER_TYPES = (
        (CUSTOMER, 'Customer'),
        (EXECUTER, 'Executer'),
    )

    user_type = models.IntegerField(choices=USER_TYPES, default=EXECUTER, verbose_name='Тип пользователя')
    balance = models.DecimalField(decimal_places=2, max_digits=7, default=0, verbose_name='Баланс')


    def __str__(self):
        return self.username

来自task.models的

任务类是：

class Task(models.Model):
    title = models.CharField(max_length=255, verbose_name='Заголовок')
    description = models.CharField(max_length=255, verbose_name='Описание')
    money = models.DecimalField(max_digits=7, decimal_places=2, default=0, verbose_name='Цена')
    assignee = models.ForeignKey('users.User', related_name='assignee', null=True, verbose_name='Исполнитель')
    created_by = models.ForeignKey('users.User', related_name='created_by', verbose_name='Кем был создан')

我应该如何运作？

Answer 1

你没有一个对象而是对象所以你需要文字或update()。最好的选择是使用F表达式，它具有良好的性能，因为它在DB上执行：

from django.db.models import F    

@receiver(post_save, sender=Task)
def my_handler(sender, instance, **kwargs):
    User.objects.filter(user_type=User.EXECUTER).update(balance=F('balance') + instance.money)

此更新user_type为Executer的所有记录，并在一个查询中更新它们的余额。

Django docs update

F expressions

您的user_type字段是IntegerField，在您的选择中，您有字符串值，因此您需要将其更改为以下内容：

class User(AbstractUser):
    CUSTOMER = 1
    EXECUTER = 2

    USER_TYPES = (
        (CUSTOMER, 'Customer'),
        (EXECUTER, 'Executer'),
    )

    user_type = models.IntegerField(choices=USER_TYPES, default=EXECUTER, verbose_name='Тип пользователя')
    balance = models.DecimalField(decimal_places=2, max_digits=7, default=0, verbose_name='Баланс')

Answer 2

在User上过滤后会得到很多对象，因此您需要迭代并保存

@receiver(post_save, sender=Task)
def my_handler(sender, instance, **kwargs):
    executors = User.objects.filter(user_type='Executer')

    for executor in executors:
        prev_value=executor.balance
        executor.balance = float(Task.money) + float(prev_value)
        executor.save()

在Django和模型中发出信号post_save

2 个答案: