FOREIGN KEY 约束失败，为什么会出现此错误？

Question

我正在创建一个博客，现在我在 cmets 部分工作，我在编辑 cmets 工作，一切正常，但问题如下，每当我更新我想要重定向的视图时我对博客文章发表了评论，但每当我这样做时，我都会在标题中收到错误代码：

models.py

这里我想用我在帖子模型中的方式重定向，重定向到文章详细信息

class Post(models.Model):
    title = models.CharField(max_length= 255)
    header_image = models.ImageField(null = True, blank = True, upload_to = 'images/')
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    body = RichTextField(blank = True, null = True)
    #body = models.TextField()
    post_date = models.DateField(auto_now_add=True)
    category = models.CharField(max_length=255, default='coding')
    snippet = models.CharField(max_length=255)
    likes = models.ManyToManyField(User, related_name = 'blog_posts')

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

    def __str__(self):
        return self.title + ' | ' + str(self.author)
    
    def get_absolute_url(self):
        return reverse('app1:article-detail', args=(self.id,))

class Comment(models.Model):
    
    post = models.ForeignKey(Post, related_name="comments", on_delete=models.CASCADE)
    name = models.ForeignKey(User, on_delete=models.CASCADE)
    body = models.TextField()
    date_added = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return '%s - %s' % (self.post.title, self.name)

    def get_absolute_url(self):
        return reverse('app1:article-detail', args=(self.id,))

views.py

在这两个视图中，如果我想重定向到文章详细信息是否存储了所有 cmets，这与 post 相同，但它显示错误

class AddCommentView(CreateView):
    model = Comment
    form_class = CommentForm
    template_name = 'app1/add_comment.html'
    def form_valid(self, form):
        form.instance.post_id = self.kwargs['pk']
        form.instance.name = self.request.user
        return super().form_valid(form)
    #fields = '__all__'
    success_url = reverse_lazy('index')

class UpdateCommentView(UpdateView):
    model = Comment
    template_name = 'app1/update_comment.html'
    form_class = CommentForm

    def form_valid(self, form):
        form.instance.post_id = self.kwargs['pk']
        form.instance.name = self.request.user
        return super().form_valid(form)

追溯

Traceback (most recent call last):
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\sqlite3\base.py", line 396, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: FOREIGN KEY constraint failed

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\core\handlers\exception.py", line 34, in inner
    response = get_response(request)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\core\handlers\base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\core\handlers\base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\views\generic\base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\views\generic\base.py", line 97, in dispatch
    return handler(request, *args, **kwargs)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\views\generic\edit.py", line 194, in post
    return super().post(request, *args, **kwargs)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\views\generic\edit.py", line 142, in post
    return self.form_valid(form)
  File "C:\Users\snin2\Desktop\basura\lapagina\app1\views.py", line 24, in form_valid
    return super().form_valid(form)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\views\generic\edit.py", line 125, in form_valid
    self.object = form.save()
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\forms\models.py", line 459, in save
    self.instance.save()
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\models\base.py", line 745, in save
    self.save_base(using=using, force_insert=force_insert,
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\models\base.py", line 782, in save_base
    updated = self._save_table(
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\models\base.py", line 864, in _save_table
    updated = self._do_update(base_qs, using, pk_val, values, update_fields,
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\models\base.py", line 917, in _do_update
    return filtered._update(values) > 0
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\models\query.py", line 771, in _update
    return query.get_compiler(self.db).execute_sql(CURSOR)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\models\sql\compiler.py", line 1492, in execute_sql
    cursor = super().execute_sql(result_type)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\models\sql\compiler.py", line 1144, in execute_sql
    cursor.execute(sql, params)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 100, in execute
    return super().execute(sql, params)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "C:\Users\snin2\anaconda3\envs\MyDjangoEnv\lib\site-packages\django\db\backends\sqlite3\base.py", line 396, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: FOREIGN KEY constraint failed
[10/Aug/2020 16:15:21] "POST /app1/update_comment/10 HTTP/1.1" 500 179169

Answer 1

如果您直接从数据库或管理站点中删除了任何信息，那里可能会出现错误。