使用OneToOneField扩展模型 [英] Extend a model using OneToOneField

问题描述

我正在尝试扩展 django-taggit Tag 模型上有一个 added_by (用户的ForeignKey)字段，因此我可以查询特定用户添加的所有标签.因此，我创建了一个应用程序，并在models.py中创建了另一个模型，称为 MyTag ，并在其上添加了一个OneToOneField来进行 Tag :

I'm trying to extend django-taggit Tag model to have an added_by (ForeignKey to User) field on it, so I can query all tags added by a particular user. So, I have created an app and in models.py there I have created another model, called MyTag and I have a OneToOneField to Tag on it:

from django.contrib.auth.models import User
from django.db import models
from django.db.models.signals import post_save
from django.dispatch import receiver
from taggit.models import Tag


class MyTag(models.Model):
    tag = models.OneToOneField(Tag, on_delete=models.CASCADE)
    added_by = models.ForeignKey(User, on_delete=models.CASCADE)

@receiver(post_save, sender=Tag)
def create_tag(sender, instance, created, **kwargs):
    if created:
        MyTag.objects.create(tag=instance, added_by=???)

@receiver(post_save, sender=Tag)
def save_tag(sender, instance, **kwargs):
    instance.mytag.save()

问题是，我无法从models.py内部访问 request.user .

The issue is, I can't access request.user from inside models.py.

如何克服该问题，即如何正确扩展django-taggit的 Tag 模型以在其上具有add_by字段?

How do I overcome the issue, i.e. how do I properly extend django-taggit's Tag model to have added_by field on it?

推荐答案

我建议使用继承代替OneToOneField.

I would recommend using inheritance instead of OneToOneField.

from taggit.models import Tag

class MyTag(Tag):
    added_by = models.ForeignKey(User, on_delete=models.CASCADE)

现在， MyTag 模型继承了 Tag 模型的所有属性和方法.此处的更多信息: https://docs.djangoproject.com/en/2.2/topics/db/models/#model-inheritance

Now the MyTag model inherits all the properties and methods of the Tag model. More info here: https://docs.djangoproject.com/en/2.2/topics/db/models/#model-inheritance

现在，您可以在视图中创建MyTag的新实例:

Now to create a new instance of MyTag you can do in your view:

MyTag.objects.create(added_by=request.user , [... other Tag properties])

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