添加到多对一关系时运行自定义代码

Question

from django.db import models

class Reporter(models.Model):
    pass

class Article(models.Model):
    reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE, null=True)

现在每当我向记者添加文章时（如下所示）我想运行一些自定义代码，我应该覆盖什么方法（不更改 bulk=True）？

>>> new_article = Article.objects.create()
>>> new_reporter = Reporter.objects.create()
>>> new_reporter.article_set.add(new_article, bulk=True)

Answer 1

答案取决于您如何在应用程序中创建对象，这将在第一次将文章添加到报告器时运行代码

class Article(models.Model):
    reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE)

    def save(self, *args, **kwargs):
        if self.reporter:
            if not self.reporter.article__set: 
                #do your code here
        super(Article, self).save(*args, **kwargs)

如果记者上的文章发生变化，这将运行代码

class Article(models.Model):
    reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE)

    def save(self, *args, **kwargs):
        if self.reporter:
            if not self.reporter.article__set is self: 
                #do your code here
        super(Article, self).save(*args, **kwargs)

还没有测试过，但逻辑似乎不错