尝试删除时Django FieldError用户

问题描述：

我在删除用户时出现问题（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，他们直接从模型创建数据库，但是当我试图从正常的，正确迁移的数据库中删除现有条目时，会发生同样的情况。尝试删除时Django FieldError用户

首先我创建了一个用户：

user = User.objects.create_user('testing', '[email protected]', 'testpass')

而且我只要致电：

user.delete()

而且它崩溃的delete（）方法中。用户甚至不需要添加相关的UserImage，它仍然崩溃。最初我以为它是由相关对象引起的，因为例外情况表示添加“加入”是不允许的，“添加”是UserImage上的字段。任何帮助表示赞赏，因为我看着它的时间，并不能找到病因:(

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.

您已完成所有迁移？如果您尝试完全删除用户图像的FK，那么它会起作用吗？ – Jonathan

@Jonathan是的，我也尝试过从头开始迁移。我刚刚尝试过，我仍然遇到同样的错误。 – Kukosk

我现在更接近这个问题，我试图删除所有与用户类的模型关系，它的工作原理，所以我把它们放回去，试图找出是哪个导致问题，并发现它实际上是我的论坛模型造成它，我可能甚至知道为什么。 – Kukosk

答

好，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',

当我将其删除或更改为：

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

尝试删除时Django FieldError用户

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