Django admin随机报OrganizationGroups无指向auth.User外键异常

问题现象 #

Django admin后台会随机抛出如下异常：organizations.OrganizationGroups has no ForeignKey to 'auth.User'，同类异常也会在系统其他应用中出现，报错格式统一为organizations.OrganizationGroups has no ForeignKey to 'app.Model'。

运行环境 #

• Django Version: 3.2.13
• Python Version: 3.9.2

相关代码 #

OrganizationGroups 模型定义 #

class OrganizationGroups(models.Model):
    id = models.BigAutoField(primary_key=True)
    organization = models.ForeignKey(
        Organization, models.DO_NOTHING, null=True, blank=True
    )
    group = models.ForeignKey(Group, models.CASCADE, blank=True, null=True)

    class Meta:
        db_table = 'organization_groups'
        unique_together = (('organization', 'group'),)

    def __str__(self) -> str:
        return self.organization.name

自定义UserAdmin配置 #

from django.contrib.admin import ModelAdmin, register
from django.contrib.auth.admin import UserAdmin as BaseUserAdmin
from django.contrib.auth.models import User
from django.http import HttpRequest

from apps.organizations.models import OrganizationGroups
from apps.users.forms import UserForm
from apps.users.models import *

@register(User)
class UserAdmin(BaseUserAdmin):
    # 前端页面配置
    actions = None
    fieldsets = (('Users', {'fields': ('username',)}),)
    form = UserForm
    list_display = ('username', 'is_active')
    list_filter = ('is_active',)
    list_per_page = 10
    ordering = ('username',)
    readonly_fields = ('username',)

    # 重写方法
    def get_fieldsets(self, request: HttpRequest, obj=None):
        if not obj:
            return self.add_fieldsets

        if request.user.is_superuser:
            perm_fields = (
                'is_active',
                'is_superuser',
                'groups',
                'user_permissions'
            )
        else:
            perm_fields = (
                'is_active',
                'groups',
                'user_permissions'
            )

        return [
            (None, {'fields': ('username',)}),
            (('Permisos'), {'fields': perm_fields}),
            (('Fechas importantes'), {'fields': ('last_login', 'date_joined')})
        ]

    def get_form(self, request, obj=None, **kwargs):
        form = super(UserAdmin, self).get_form(request, obj, **kwargs)
        form.user = request.user
        if not request.user.is_superuser:
            if 'groups' in form.base_fields:
                groups = form.base_fields['groups']
                try:
                    user = LegacyUser.objects.get(
                        user_name=request.user.username
                    )
                    og_not_in_users_org = OrganizationGroups.objects.exclude(
                        organization=user.organization
                    )
                    exclude_group_id_list = []
                    for organization_group in og_not_in_users_org:
                        exclude_group_id_list.append(
                            organization_group.group_id
                        )
                    groups.queryset = groups.queryset.exclude(
                        id__in=exclude_group_id_list
                    )
                except LegacyUser.DoesNotExist:
                    pass
            if 'user_permissions' in form.base_fields:
                permissions = form.base_fields['user_permissions']
                permissions.queryset = permissions.queryset.exclude(
                    content_type__app_label__in=[
                        'admin', 'admin_interface', 'auth', 'contenttypes',
                        'organizations', 'sessions'
                    ]
                )
        return form

    def get_queryset(self, request: HttpRequest):
        qs = super().get_queryset(request)
        if request.user.is_superuser:
            return qs
        try:
            user = LegacyUser.objects.get(user_name=request.user.username)
            legacy_user_organization = LegacyUser.objects.filter(
                organization=user.organization
            )
            user_name_list = []
            for user in legacy_user_organization:
                user_name_list.append(user.user_name)
            return qs.filter(username__in=user_name_list)
        except LegacyUser.DoesNotExist:
            # 默认判定为超级用户
            return qs

    def has_add_permission(self, request: HttpRequest):
        return False

    def has_delete_permission(self, request: HttpRequest, obj=None) -> bool:
        return False

UserForm表单定义 #

from django.contrib.auth.models import User
from django.core.exceptions import ValidationError
from django.forms.models import ModelForm

class UserForm(ModelForm):
    def __init__(self, *args, **kwargs):
        super(UserForm, self).__init__(*args, **kwargs)
        try:
            user: User = User.objects.get(id=self.instance.pk)
            if user == self.user:
                if self.user.is_superuser:
                    self.fields['is_superuser'].disabled = True
                self.fields['is_active'].disabled = True
                self.fields['groups'].disabled = True
                self.fields['user_permissions'].disabled = True
                self.fields['last_login'].disabled = True
                self.fields['date_joined'].disabled = True
        except User.DoesNotExist:
            pass

    def clean(self):
        for string, field in self.fields.items():
            if field.disabled is True:
                raise ValidationError(
                    'No puede realizar modificaciones a su propio usuario.',
                    'own_user_is_not_editable'
                )
        return super().clean()

完整报错栈 #

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/dist-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.9/dist-packages/django/core/handlers/base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 616, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/django/utils/decorators.py", line 130, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/django/views/decorators/cache.py", line 44, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/sites.py", line 232, in inner
    return view(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 1660, in change_view
    return self.changeform_view(request, object_id, form_url, extra_context)
  File "/usr/local/lib/python3.9/dist-packages/django/utils/decorators.py", line 43, in _wrapper
    return bound_method(*args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/django/utils/decorators.py", line 130, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 1540, in changeform_view
    return self._changeform_view(request, object_id, form_url, extra_context)
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 1604, in _changeform_view
    formsets, inline_instances = self._create_formsets(request, obj, change=True)
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 1961, in _create_formsets
    for FormSet, inline in self.get_formsets_with_inlines(*get_formsets_args):
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 799, in get_formsets_with_inlines
    yield inline.get_formset(request, obj), inline
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 2059, in get_formset
    fields = flatten_fieldsets(self.get_fieldsets(request, obj))
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 337, in get_fieldsets
    return [(None, {'fields': self.get_fields(request, obj)})]
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 328, in get_fields
    form = self._get_form_for_get_fields(request, obj)
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 2144, in _get_form_for_get_fields
    return self.get_formset(request, obj, fields=None).form
  File "/usr/local/lib/python3.9/dist-packages/django/contrib/admin/options.py", line 2141, in get_formset
    return inlineformset_factory(self.parent_model, self.model, **defaults)
  File "/usr/local/lib/python3.9/dist-packages/django/forms/models.py", line 1069, in inlineformset_factory
    fk = _get_foreign_key(parent_model, model, fk_name=fk_name)
  File "/usr/local/lib/python3.9/dist-packages/django/forms/models.py", line 1038, in _get_foreign_key
    raise ValueError(
Exception Type: ValueError at /auth/user/1/change/
Exception Value: 'organizations.OrganizationGroups' has no ForeignKey to 'auth.User'.

问题原因 #

报错核心触发逻辑：Django admin渲染User模型编辑页时，会自动探测所有已注册模型，尝试将存在外键指向当前模型的类作为内联（Inline）加载。OrganizationGroups是Organization和Group的多对多中间表，而Group和User本身存在多对多关联，Django的自动探测逻辑受模型加载顺序影响，会随机误将OrganizationGroups识别为User的关联内联模型，生成内联表单集时发现OrganizationGroups没有指向auth.User的外键，就会抛出异常。这也是报错随机出现、会在其他app复现同类错误的根本原因。

修复方案 #

1. 在自定义的UserAdmin类中显式指定内联配置为空，覆盖默认的自动探测逻辑：

@register(User)
class UserAdmin(BaseUserAdmin):
    inlines = []  # 新增该行即可阻断错误的自动内联加载
    # 其余原有配置保持不变

2. 对其他出现同类报错的模型，在对应ModelAdmin中同样显式指定inlines配置，不要依赖Django的自动内联探测，避免多对多中间表被误识别。
3. 如果确实需要在User编辑页展示关联的组织分组数据，不要直接将OrganizationGroups作为内联使用（它没有到User的外键，不符合内联模型要求），可以自定义展示字段或者通过Group做二次关联查询实现，不要走默认的inlineformset生成逻辑。

内容的提问来源于stack exchange，提问作者Santiago Muñoz