Django 2.2.2：管理员 "Manager isn't accessible via (Model) instances"

Question

你好，

我刚刚创建了两个模型：

models.py

from django.db import models
from django.contrib.auth.models import User
import uuid
from uuid_upload_path import upload_to
from django.core.exceptions import ValidationError
from django.utils.functional import cached_property
from django.utils.translation import gettext_lazy as _


class StorageObject(models.Model):
    name = models.CharField(max_length=200)
    text = models.TextField(blank=True)
    slug = models.UUIDField(default=uuid.uuid4)
    display = models.BooleanField(default=True)
    owner = models.ForeignKey(User, on_delete=models.CASCADE)
    # types
    file = models.FileField(upload_to=upload_to, blank=True, null=True)
    image = models.ImageField(upload_to=upload_to, blank=True, null=True)
    link = models.URLField(blank=True)

    @cached_property
    def file_type(self):
        if self.file:
            return 1
        elif self.image:
            return 2
        elif self.link:
            return 3

    def clean(self):
        if self.file and (self.image or self.link):
            raise ValidationError(_('Storage Objects can only contain one storage type each'))
        elif self.image and (self.link or self.file):
            raise ValidationError(_('Storage Objects can only contain one storage type each'))
        elif self.link and (self.file or self.image):
            raise ValidationError(_('Storage Objects can only contain one storage type each'))
        if not (self.link or self.image or self.file):
            raise ValidationError(_('Storage Objects must contain exactly one storage type'))

    def __str__(self):
        return '%s (by %s)' % (self.name, self.owner)


class Collection(models.Model):
    name = models.CharField(max_length=200)
    active = models.BooleanField(default=True)
    objects = models.ManyToManyField(StorageObject)
    owner = models.ForeignKey(User, on_delete=models.CASCADE)

正如标题所说，每当我尝试通过 admin-interface 创建 Collection 时，我都会收到 AttributeError。然而，创建 StorageObject 工作得很好并且得到了适当的清理。

我用谷歌搜索了这条消息，大多数人似乎忘记了某处的实例括号（如 StorageObject() ）。可能是我瞎了，就是找不到错误。

所以我继续删除了我的自定义函数 file_type 和 clean，但仍然是相同的结果。

我在这里错过了什么？感谢您的宝贵时间！

堆栈

 File "C:\Users\[..]\venv\lib\site-packages\django\db\models\manager.py", line 176, in __get__
        raise AttributeError("Manager isn't accessible via %s instances" % cls.__name__)
    AttributeError: Manager isn't accessible via Collection instances

Answer 1

不要在您的模型上添加字段 objects，这与也称为 objects 的模型 Manager 冲突。 Collection.objects 应该 return 一个 Manager 除非你决定给它一个不同的名字（见 here）。

Django 2.2.2：管理员 "Manager isn't accessible via (Model) instances"

Django 2.2.2: "Manager isn't accessible via (Model) instances" on Admin

django

django-models

python-3.7