在Django中保存模型给我“Warning：Field”id'没有默认值“ [英] Saving a model in Django gives me "Warning: Field 'id' doesn't have a default value"

问题描述

我在Django中有一个非常基本的模型：

  class Case（models.Model）：
 name = models.CharField（max_length = 255）
 created_at = models.DateTimeField（default = datetime.now）
 updated_at = models.DateTimeField（default = datetime.now）
 
 def save （self）：
 if self.created_at == None：
 self.created_at = datetime.now（）
 self.updated_at = datetime.now（）
 super（Case， self）.save（）
 
 class Meta：
 db_table = u'cases'
  

因为我没有指定PK，Django为我照顾了。我看到我的数据库中的字段被称为id，标记为主键和自动增量。我觉得奇怪的是得到这个警告，因为DB和模型结束的一切都很酷。错误是：

  _mysql_exceptions.Warning 
 
警告：字段'id'没有默认值
  

保存时的工作是将id设置为0.它会使警告和自从MySQL处理它以来，id被正确设置。

  case = Case（）
 case.id = 0 #ugly解决方法为 - 警告：字段'id'没有默认值
 case.name = request.POST [u'case [name]'] 
 case.save（）
  

此解决方案的问题是：

1. 这是丑的


2. 新的PK在保存后无法访问，这使得
   无法正常序列化

有没有人知道如何解决这个问题？

我正在运行：

  Python 2.7.2 
 django.VERSION（1，3，1，'final'，0）
 mysql Ver 14.14 Distrib 5.1.45，for apple-darwin10。 2.0（i386）使用readline 5.1 
 MySQL_py thon-1.2.3-py2.7-macosx-10.4-x86_64.egg 
  

我的创建表看起来像这样：

  CREATE TABLE`cases`（
`id` int（11）NOT NULL AUTO_INCREMENT，
`name` varchar（255）NOT NULL，
`created_at` datetime NOT NULL，
`updated_at` datetime NOT NULL，
 PRIMARY KEY（`id`）
 ）ENGINE = MyISAM AUTO_INCREMENT = 45 DEFAULT CHARSET = latin1 
  

解决方案

我想在这个问题上展开，因为本周我遇到了这个问题。我得到这个相同的错误，看看模型定义和SQL定义显​​示：

1. 模型影响没有明确定义PK或明确定义了PK（都有问题）。这似乎无关紧要。




2. 受影响的表与OP中的id定义相同，即 id int（11）NOT NULL AUTO_INCREMENT 。 PRIMARY KEY 按预期设置。




3. 查看MySQL查询日志我有一些这样的程度：

    code> INSERT INTO`x`（...）VALUES（...）
    SHOW WARNINGS 
    ROLLBACK 
     

   单独运行查询是成功的， SHOW WARNINGS 反映了OP中提到的警告。

然而，我遇到了一个MySQL端修复程序， http://webit.ca/2012/01/field-id-doesnt-have-a-default-value/ 提到，重置id定义（粗略一瞥似乎没有任何不同）解决了这个问题。我无法解释为什么这样做，但它解决了这个问题，没有任何额外的代码更改。我相信这可能在某种程度上与删除记录有关，但是整个问题对我来说似乎是不合理的。

I have a very basic model in Django:

class Case(models.Model):
    name = models.CharField(max_length=255)
    created_at = models.DateTimeField(default=datetime.now)
    updated_at = models.DateTimeField(default=datetime.now)

    def save(self):
        if self.created_at == None:
             self.created_at = datetime.now()
        self.updated_at = datetime.now()
        super(Case, self).save()

    class Meta:
        db_table = u'cases'

Because I did not specify the PK, Django took care of that for me. I see the field in my database which is called "id", marked as a primary key and auto-increment. I find odd to be getting that warning since everything is cool on the DB and model end. The error is:

_mysql_exceptions.Warning

Warning: Field 'id' doesn't have a default value

My work around when saving is to set the id to 0. It kills the warning and the id gets set properly anyway since MySQL handles it.

case = Case()
case.id = 0 #ugly workaround for - Warning: Field 'id' doesn't have a default value
case.name = request.POST[u'case[name]']
case.save()

The issue with this solution is:

1. It's ugly
2. The new PK is inaccessible after saving which makes it impossible to serialize properly

Does anyone know how to fix this?

I'm running:

Python 2.7.2
django.VERSION (1, 3, 1, 'final', 0)
mysql  Ver 14.14 Distrib 5.1.45, for apple-darwin10.2.0 (i386) using readline 5.1
MySQL_python-1.2.3-py2.7-macosx-10.4-x86_64.egg

And my create table looks like this:

CREATE TABLE `cases` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=45 DEFAULT CHARSET=latin1

解决方案

I'd like to expand on this question as I've ran into it this week. I was getting this same exact error and taking a look at the model definition and SQL definition showed that:

1. The models affected either had no PK explicitly defined or had a PK explicitly defined (both had problems). This alone seemed unrelated.

2. The tables affected had the "id" definition as in the OP, i.e. id int(11) NOT NULL AUTO_INCREMENT. The PRIMARY KEY is set as expected.

3. Looking into the MySQL query log I got something to this extent:

   INSERT INTO `x` (...) VALUES (...)
   SHOW WARNINGS
   ROLLBACK
   

   Running the query individually is successful, and SHOW WARNINGS reflects the warning noted in the OP.

I however came across a MySQL-end fix, http://webit.ca/2012/01/field-id-doesnt-have-a-default-value/ mentioned that resetting the id definition (which at a cursory glance appears to not be any different) fixes the problem. I can't explain why this works, but it addresses the problem without any additional code changes. I believe this may be in some way linked to removing records, but the whole issue seems non-sensical to me.

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