使用post_save信号处理程序访问新创建的模型实例的相关数据 [英] Access to related data of newly created model instance using post_save signal handler

问题描述

通过管理面板创建 Entry 模型的新实例时，我需要发送电子邮件。因此，在 models.py 中，我有：

I need to send an e-mail when new instance of Entry model is created via admin panel. So in models.py I have:

class Entry(models.Model):   
    attachments = models.ManyToManyField(to=Attachment, blank=True)
    #some other fields
    #...
    sent = models.BooleanField(editable=False, default=False)

然后，我注册了post_save处理函数：

Then I'm registring post_save handler function:

def send_message(sender, instance, **kwargs):
    if not instance.sent:
        #sending an e-mail message containing details about related attachments
        #...
        instance.sent = True
        instance.save()

post_save.connect(send_message, sender=Entry)  

它可以工作，但是正如我之前提到的，我还需要访问相关附件以将其详细信息包括在信息。不幸的是，即使实际添加了附件， instance.attachments.all（）也会在 send_message 函数内返回空列表。

It works, but as I mentioned before, I also need to access related attachments to include their details in the message. Unfortunatelly instance.attachments.all() returns empty list inside send_message function even if attachments were actually added.

我发现，发送post_save信号时，尚未保存已保存模型的相关数据，因此无法从该位置获取相关附件。
问题是：我是否可以使用信号或任何其他方式来完成此操作，还是必须将此电子邮件发送代码放在外面，例如，覆盖 Entry <的管理面板更改视图？ / code>模型？

As I figured out, when the post_save signal is sent, related data of saved model isn't saved yet, so I can't get related attachments from that place. Question is: am I able to accomplish this using signals, or in any other way, or do I have to put this email sending code outside, for example overriding admin panel change view for Entry model?

推荐答案

您应该可以通过覆盖 save_model（）方法。您可以在其中发送电子邮件，也可以发出自定义信号，触发您的处理程序发送电子邮件。

You should be able to do this by overriding the save_model() method on the ModelAdmin. You could either send your email in there or fire a custom signal which triggers your handler to send the email.

如果您有内联，我相信您需要使用 save_formset（）。

If you have inlines, I believe you need to use save_formset() instead.

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