【发布时间】：2021-11-02 15:45:50
【问题描述】：
堆栈溢出。
我有一个管理项目列表和标签（类别）的 Django 应用程序。它们与Item 模型上的ManyToMany 字段相关。以下代码是模型中的相关代码
我使用 PostgreSQL 作为我的数据库。
#models.py
class Tag(models.Model):
title = models.CharField(max_length=300, unique=True)
slug = models.SlugField(max_length=300, blank=True, null=True, unique=True)
objects = TagManager()
def generate_token(self):
self.slug = get_random_string(length=15)
return self.slug
def save(self, *args, **kwargs):
if self.slug is None:
self.generate_token()
super().save(*args, **kwargs)
还有Item 模型
class Item(models.Model):
seller = models.ForeignKey(User,related_name='seller', on_delete=models.CASCADE)
#the following lines are the problem lines
tag = models.ManyToManyField(Tag, related_name='tag', blank=True)
slug = models.SlugField(max_length=30, blank=True, null=True, unique=True)
objects = ItemManager()
def generate_token(self):
self.slug = get_random_string(length=15)
return self.slug
def save(self, *args, **kwargs):
if self.slug is None:
self.generate_token()
super().save(*args, **kwargs)
此代码运行良好，直到我尝试从 Django 管理页面添加项目。我填写了所有字段，从<select> 菜单中添加了两个标签并尝试保存。
但是，我收到了以下错误消息
关系“item_item”的“tag_id”列中的空值违反了非空约束
和
DETAIL：失败行包含 (18, Item Name Here, This is description, 40.00, items/pattern.png, lXBjgo70QIrI8aF, 1, null)。
这是完整的回溯
Environment:
Request Method: POST
Request URL: http://127.0.0.1:8000/admin/item/item/add/
Django Version: 3.2.6
Python Version: 3.9.6
Installed Applications:
['django.contrib.admin',
'django.contrib.sites',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'cameloapp',
'user',
'item',
'allauth',
'allauth.account',
'allauth.socialaccount',
'allauth.socialaccount.providers.google',
'allauth.socialaccount.providers.twitter']
Installed Middleware:
['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']
Traceback (most recent call last):
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
The above exception (null value in column "tag_id" of relation "item_item" violates not-null constraint
DETAIL: Failing row contains (18, Item Name Here, This is the description, 40.00, items/pattern.png, lXBjgo70QIrI8aF, 1, null).
) was the direct cause of the following exception:
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
response = get_response(request)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\contrib\admin\options.py", line 616, in wrapper
return self.admin_site.admin_view(view)(*args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\utils\decorators.py", line 130, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\views\decorators\cache.py", line 44, in _wrapped_view_func
response = view_func(request, *args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\contrib\admin\sites.py", line 232, in inner
return view(request, *args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\contrib\admin\options.py", line 1657, in add_view
return self.changeform_view(request, None, form_url, extra_context)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\utils\decorators.py", line 43, in _wrapper
return bound_method(*args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\utils\decorators.py", line 130, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\contrib\admin\options.py", line 1540, in changeform_view
return self._changeform_view(request, object_id, form_url, extra_context)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\contrib\admin\options.py", line 1586, in _changeform_view
self.save_model(request, new_object, form, not add)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\contrib\admin\options.py", line 1099, in save_model
obj.save()
File "C:\Users\User\camelo\cameloapp\item\models.py", line 104, in save
super().save(*args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\models\base.py", line 726, in save
self.save_base(using=using, force_insert=force_insert,
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\models\base.py", line 763, in save_base
updated = self._save_table(
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\models\base.py", line 868, in _save_table
results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\models\base.py", line 906, in _do_insert
return manager._insert(
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\models\query.py", line 1270, in _insert
return query.get_compiler(using=using).execute_sql(returning_fields)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\models\sql\compiler.py", line 1416, in execute_sql
cursor.execute(sql, params)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\backends\utils.py", line 98, in execute
return super().execute(sql, params)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\backends\utils.py", line 66, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\backends\utils.py", line 75, in _execute_with_wrappers
return executor(sql, params, many, context)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\utils.py", line 90, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
Exception Type: IntegrityError at /admin/item/item/add/
Exception Value: null value in column "tag_id" of relation "item_item" violates not-null constraint
DETAIL: Failing row contains (18, Item Name Here, This is the description, 40.00, items/pattern.png, lXBjgo70QIrI8aF, 1, null).
抱歉所有代码块/错误
我尝试过的
我尝试了很多方法来尝试消除此错误，但都没有奏效。
- 已删除迁移
- 在两个模型的 slug 字段中添加、删除、读取
null=True - 为
blank=True做了同样的事情
这些都没有奏效。我在网上四处寻找一个预先存在的解决方案，但他们只是让我在我已经拥有的字段上添加null=True。
我很困惑为什么会发生这个错误。
tag_id 对我来说很突出，因为我假设非空错误与此有关，并且我假设 ids 是在创建对象时分配的。
提前谢谢你
【问题讨论】：
-
我创建了一个新的 PostgreSQL 数据库并将其连接到我的 Django 项目。现在一切正常。但我很担心为什么我的普通数据库决定不工作。我可以采取任何措施来修复正常的数据库吗？
标签： python django postgresql django-models django-migrations