如何根据通过 Django 生成的新主键发送电子邮件？答案

【问题标题】：How can I send an email based on a new primary key being generated through Django?如何根据通过 Django 生成的新主键发送电子邮件？
【发布时间】：2013-07-24 19:09:47
【问题描述】：

每当在 Django 中生成新的主键时，我想向用户发送一封电子邮件。我在 Models.py 中的代码：

class PurchaseOrder(models.Model):
    product = models.CharField(max_length=256)
    vendor = models.CharField(max_length=256)
    dollar_amount = models.FloatField()
    item_number = models.AutoField(primary_key=True)

我已将其编码到每次刷新页面时都可以发送电子邮件的位置

email = EmailMessage('Purchase Order System', 'your message here', to=['youremail@gmail.com'])
email.send()

但我怎样才能让每次生成新的主键时，发送一封电子邮件？

【问题讨论】：

标签： python django email key

【解决方案1】：

使用django signals。

from django.db.models import signals

def send_email_on_new_order(instance, created, raw, **kwargs):
    # Fixtures or updates are not interesting.
    if not created or raw:
        return

    # `instance` is your PurchaseOrder instance.
    email = EmailMessage('Purchase Order System', 'your message here', to=['youremail@gmail.com'])
    email.send()

signals.post_save.connect(send_email_on_new_order, sender=PurchaseOrder, dispatch_uid='send_email_on_new_order')

您必须将此代码粘贴到将在加载 django 期间执行的某个位置，例如models.py

例如models.py:

from django.core.mail import EmailMessage
from django.db import models
from django.db.models import signals

class PurchaseOrder(models.Model):
    product = models.CharField(max_length=256)
    vendor = models.CharField(max_length=256)
    dollar_amount = models.FloatField()
    item_number = models.AutoField(primary_key=True)

def send_email_on_new_order(instance, created, raw, **kwargs):
    # Fixtures or updates are not interesting.
    if not created or raw:
        return

    # `instance` is your PurchaseOrder instance.
    email = EmailMessage('Purchase Order System', 'your message here', to=['youremail@gmail.com'])
    email.send()

signals.post_save.connect(send_email_on_new_order, sender=PurchaseOrder, dispatch_uid='send_email_on_new_order')

【讨论】：

我收到一条错误消息，提示“NameError: name 'PurchaseOrder' is not defined”如果这是一个糟糕的问题，我深表歉意，因为我是 Python 和 Django 的新手。
将from django.db.models import signals 放在models.py 文件的顶部，而其余代码放在PurchaseOrder 定义的下方。检查我的答案以供参考。

【解决方案2】：

收听post_save 信号。

from django.db.models import signals
from django.dispatch import receiver

@receiver(signals.post_save, sender=PurchaseOrder)
def email_handler(sender, **kwargs):
    if kwargs['created']:
        email = EmailMessage('Purchase Order System', 'your message here', to=['youremail@gmail.com'])
        email.send()

或者在你的模型中定义一个自定义的save 方法。

class PurchaseOrder(models.Model):
    def save(self, *args, **kwargs):
        # Check if this is a new key
        if not self.pk:
            email = EmailMessage('Purchase Order System', 'your message here', to=['youremail@gmail.com'])
            email.send()
        super(PurchaseOrder, self).save(*args, **kwargs)

【讨论】：

【解决方案3】：

@voithos 是正确的，这是自定义保存是解决问题的好方法。但是，根据对问题的严格回答，从技术上讲，电子邮件是在创建主键之前发送的。这可能无关紧要，但如果确实如此，我会订购如下代码：

def save(self, *args, **kwargs):
    email = False  # Don't email by default
    # Check if this is a new key
    if not self.pk:
        email = EmailMessage('Purchase Order System', 'your message here', to=['youremail@gmail.com'])
    super(PurchaseOrder, self).save(*args, **kwargs)
    if email:  # Email was created, and we have a new Primary Key, so send now.
        email.send()

注意：如果您需要一种方法来引用新创建的实例（例如，电子邮件需要包含一个包含刚刚创建的主键的链接），我个人会使用 @kroolik 提供的信号方法。

【讨论】：