在Django管理中获取相关字段的相关字段

Question

我确实有一个带有两个外键的模型来获取target_site和target_page，但是问题是我将需要访问仅与所选的target_site相关的target_pages。最好的方法是什么？

class Link(models.Model):
    source_page = models.CharField(max_length=300)
    target_site = models.ForeignKey(
        'network.Site', on_delete=models.CASCADE, related_name='site')
    target_page = models.ForeignKey(
        'network.Page', on_delete=models.CASCADE, related_name='page')
    anchor = models.CharField(max_length=300)
    time_added = models.DateTimeField(null=True, blank=True)

    def __str__(self):
        return self.source_page

    @property
    def target_path(self):
        full_path_target = "https://" + \
            str(self.target_site) + str(self.target_page)
        return full_path_target