当我尝试删除帖子时，不断收到“IntegrityError FOREIGN KEY constraint failed”答案

【问题标题】：Keep getting "IntegrityError FOREIGN KEY constraint failed" when i am trying to delete a post当我尝试删除帖子时，不断收到“IntegrityError FOREIGN KEY constraint failed”
【发布时间】：2026-01-13 23:55:01
【问题描述】：

每次我尝试删除帖子时，我都会收到此错误，但我的删除按钮以前可以使用。我认为它与 on_delete 属性有关，但我将其值更改了几次，它仍然不起作用。

//models.py

from django.db import models
from django.conf import settings
from django.urls import reverse


User = settings.AUTH_USER_MODEL

class PostManager(models.Manager):
    def search(self, query):
        qs = self.get_queryset().filter(title__icontains=query)
        if qs:
            return qs
        return None

    def get_by_id(self, id):
        qs = self.get_queryset().filter(id=id)
        if qs.count() == 1:
            return qs.first()
        else:
            return None     


# Create your models here.
class PostModel(models.Model):
    user = models.ForeignKey(User, default=1, on_delete=models.CASCADE)
    title = models.CharField(max_length=50)
    message = models.TextField()
    date = models.DateTimeField(auto_now_add=True)
    likes = models.ManyToManyField(User, blank=True, related_name='post_likes')


    def __str__(self):
        return self.title

    objects = PostManager()

    def get_total_likes(self):
        return self.likes.count()   

    def get_absolute_url(self):
        return reverse("birdpost:detail", kwargs={"id": self.id})

    def get_like_url(self):
        return reverse("birdpost:like-toggle", kwargs={"id": self.id})

    def get_delete_url(self):
        return reverse("birdpost:delete_post", kwargs={"id": self.id})

//views.py

def del_post(request, id):
    obj = get_object_or_404(PostModel, id=id)
    if request.user != obj.user:
        print("Ooh no looks like this post is not yours... ")
    else:
        obj.delete()

    return redirect("home")

环境：

请求方法：GET 请求网址：http://localhost:8000/post/4/delete

Django 版本：2.2.1 Python版本：3.6.8 已安装的应用程序：

['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'accounts',
 'birdpost',
 'search']

已安装的中间件：

['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']

追溯：

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/backends/base/base.py" in _commit
  240.                 return self.connection.commit()

The above exception (FOREIGN KEY constraint failed) was the direct cause of the following exception:

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/grey/Desktop/python/birds/src/birdpost/views.py" in del_post
  104.      obj.delete()

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/models/base.py" in delete
  919.         return collector.delete()

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/models/deletion.py" in delete
  318.                             sender=model, instance=obj, using=self.using

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/transaction.py" in __exit__
  240.                         connection.commit()

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/backends/base/base.py" in commit
  262.         self._commit()

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/backends/base/base.py" in _commit
  240.                 return self.connection.commit()

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/utils.py" in __exit__
  89.                 raise dj_exc_value.with_traceback(traceback) from exc_value

File "/home/grey/Desktop/python/birds/virtualenv/lib/python3.6/site-packages/django/db/backends/base/base.py" in _commit
  240.                 return self.connection.commit()

Exception Type: IntegrityError at /post/4/delete
Exception Value: FOREIGN KEY constraint failed

【问题讨论】：

请发布完整的堆栈跟踪。
它现在就在那里。
如果您还将on_delete=models.CASCADE arg 添加到您的likes 字段怎么办？
Like 字段是 ManyToManyField 字段，每次我在其中放置 on_delete 时都会出错：TypeError: __init__() got an unexpected keyword argument 'on_delete'
我认为您不能在 ManyToManyField 上放置 on_delete 参数。对于 ForeignKey，您必须明确指定它在最初未填充时可以为 null，但同样不适用于 m2m 关系，因此不需要 on_delete。也许这篇文章会有所帮助？ *.com/questions/54655757/…

标签： python django

【解决方案1】：

我像@Na'aman Hirschfeld 所说的那样删除了 default=1，并删除了我所有的迁移和数据库。现在它工作正常。

【讨论】：

【解决方案2】：

尝试删除默认值=1。我不知道在没有选择字段的情况下设置默认值是否可行。

【讨论】：

不知道它是否有效，但我删除了 default=1，并删除了我所有的迁移和我的数据库。现在它工作正常。