Question

我在删除用户时遇到问题（仅用于测试），我不确定发生了什么。我正在运行python 3.6和Django 1.11.6。我的测试不使用数据库迁移，它们直接从模型创建数据库，但当我尝试从正常，正确迁移的数据库中删除现有条目时，也会发生同样的情况。

首先我创建一个用户：

user = User.objects.create_user('testing', 'testing@test.com', 'testpass')

我只是打电话：

user.delete()

它在delete（）方法中崩溃了。用户甚至不需要添加相关的UserImage，它仍然会崩溃。最初我认为它是由相关对象引起的，因为例外情况说“不允许加入'加''，而'添加'是UserImage上的字段。任何帮助都是值得赞赏的，因为我看了几个小时，找不到原因:(

models.py

class UserManager(BaseUserManager):
    def _create_user(self, username, email, password, **extra_fields):
        if not username:
            raise ValueError('Username must be set.')

        email = self.normalize_email(email)
        user = self.model(username=username, email=email, **extra_fields)
        user.set_password(password)
        user.save(using=self._db)

        return user

    def create_user(self, username, email=None, password=None, **extra_fields):
        return self._create_user(username, email, password, **extra_fields)


class User(AbstractBaseUser):
    class Meta:
        verbose_name = _('user')
        verbose_name_plural = _('users')

    USERNAME_FIELD = 'username'
    REQUIRED_FIELDS = ['email']
    USERNAME_ALLOWED_REGEX = r'\w._-'

    objects = UserManager()

    username = models.CharField(
        db_index=True,
        max_length=10, unique=True,
        help_text=_('10 characters or fewer. Letters, digits and ._- only.'),
        validators=[
            validators.RegexValidator(r'^[' + USERNAME_ALLOWED_REGEX + r']+$', _('Enter a valid username.'), 'invalid')
        ],
    )

    first_name = models.CharField(
        max_length=30, blank=True,
        help_text=_('Maximum 30 characters.'),
    )

    last_name = models.CharField(
        max_length=30, blank=True,
        help_text=_('Maximum 30 characters.'),
    )

    email = models.EmailField(
        unique=True,
    )

    is_active = models.BooleanField(
        default=True,
    )

    joined = models.DateTimeField(
        auto_now_add=True, editable=False,
    )

    avatar = models.OneToOneField(
        'UserImage',
        null=True, blank=True, related_name='avatar_user',
        on_delete=models.SET_NULL,
        )

    def add_image(self, name, content, save=True):
        new_image = UserImage(user=self)
        new_image.save_images(name, content, save=save)

        return new_image

class UserImage(models.Model):
    class Meta:
        verbose_name = _('user_image')
        verbose_name_plural = _('user_images')
        ordering = 'id',

    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        related_name='images',
        on_delete=models.CASCADE,
    )

    added = models.DateTimeField(
        auto_now_add=True, editable=False,
    )

    image = RenamedProcessedImageField(
        upload_to=user_image_path,
        processors=(ResizeToFit(2048, 2048, upscale=False),),
        format='JPEG',
        options={'quality': 100},
        )

    def save_images(self, name, content, save=True):
        self.image.save(name, content, save=False)

        if save:
            self.full_clean(validate_unique=False)
            self.save()

例外：

Traceback (most recent call last):
  File "***/users/tests.py", line 237, in test_files_on_delete_rule
    user.delete()
  File "***/python3.6/site-packages/django/db/models/base.py", line 973, in delete
    collector.collect([self], keep_parents=keep_parents)
  File "***/python3.6/site-packages/django/db/models/deletion.py", line 222, in collect
    elif sub_objs:
  File "***/python3.6/site-packages/django/db/models/query.py", line 254, in __bool__
    self._fetch_all()
  File "***/python3.6/site-packages/django/db/models/query.py", line 1118, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "***/python3.6/site-packages/django/db/models/query.py", line 53, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch)
  File "***/python3.6/site-packages/django/db/models/sql/compiler.py", line 871, in execute_sql
    sql, params = self.as_sql()
  File "***/python3.6/site-packages/django/db/models/sql/compiler.py", line 423, in as_sql
    extra_select, order_by, group_by = self.pre_sql_setup()
  File "***/python3.6/site-packages/django/db/models/sql/compiler.py", line 47, in pre_sql_setup
    order_by = self.get_order_by()
  File "***/python3.6/site-packages/django/db/models/sql/compiler.py", line 298, in get_order_by
    field, self.query.get_meta(), default_order=asc))
  File "***/python3.6/site-packages/django/db/models/sql/compiler.py", line 601, in find_ordering_name
    field, targets, alias, joins, path, opts = self._setup_joins(pieces, opts, alias)
  File "***/python3.6/site-packages/django/db/models/sql/compiler.py", line 634, in _setup_joins
    pieces, opts, alias)
  File "***/python3.6/site-packages/django/db/models/sql/query.py", line 1417, in setup_joins
    names, opts, allow_many, fail_on_missing=True)
  File "***/python3.6/site-packages/django/db/models/sql/query.py", line 1385, in names_to_path
    " not permitted." % (names[pos + 1], name))
django.core.exceptions.FieldError: Cannot resolve keyword 'max' into field. Join on 'added' not permitted.

Answer 1

好的，所以我发现问题实际上是由我的Topic模型上的排序定义引起的：

class ForumTopic(models.Model):
    class Meta:
        ordering = '-forum_posts__added__max',

当我删除它或将其更改为：

时，它可以正常工作

class ForumTopic(models.Model):
    class Meta:
        ordering = '-id',

尝试删除用户时出现Django FieldError

1 个答案: