将datetime字段转换为主键会导致致命错误 [英] Taking a datetime field into primary key throws fatal error

问题描述

我想使用两个外键和datetime字段的组合作为我的组合主键。

I would like to use the combination of two foreign keys plus the datetime field as my combined primary key.

但是我得到一个

可追踪的致命错误：类DateTime的对象不能被转换
到
中的字符串C：\development\xampp\htdocs\\ \\ happyfaces\vendor\doctrine\orm\lib\Doctrine\ORM\UnitOfWork.php
line 1337

Catchable Fatal Error: Object of class DateTime could not be converted to string in C:\development\xampp\htdocs\happyfaces\vendor\doctrine\orm\lib\Doctrine\ORM\UnitOfWork.php line 1337

当我这样做一旦我从我的YML实体声明中删除了 id：true ，则一切正常。

when I do so. As soon as I remove the id: true from my YML entity declaration everything works fine again.

这里出现的问题？对我而言似乎是一个Symfony2或Doctrine2错误，因为如果我不将datetime列声明为主键的一部分，datetime在数据库中设置好。

What is the problem that occurs here? It seems to be rather a Symfony2 or a Doctrine2 bug to me, because the datetime is set fine in the database if I don't declare the datetime column to be part of the primary key.

任何人都可以帮助或建议？

Can anyone help or advise?

推荐答案

不可能，不推荐。主要关注基本数据类型，例如 Integer 或 String 。最多的RDMS系统喜欢整数作为最大性能的主键。

Its not possible and not recommended. For primary key focus on primitive data types such as Integer or String. The most RDMS System prefer Integer as primary key for maximum performance.

查看： http://doctrine-orm.readthedocs.org/en/2.1/tutorials/composite-primary-keys。 html

可能通过添加新的Doctrine数据类型可以解决方法。使用 __ toString（）函数，但我认为，Doctrine将强制您仅使用原始数据类型。

Maybe a workaround could work by adding a new Doctrine data type. With a __toString() function, but I think Doctrine will force you to use primitive data types only.

class Foo
{
    private $bar = 'test';

    public function __toString()
    {
        return $this->bar;
    }
}

echo new Foo();

您的错误一般意味着 DateTime 没有 __ toString（）函数或不兼容字符串。我从未测试过使用自定义数据类型作为主键。所以你必须自己尝试。

Your error means in general DateTime has no __toString() function or is not string compatible. I never tested it to use a custom data type as primary key. So you've to try it yourself.

看看： http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/types.html

另一个尝试是使用 String 作为主键，并将 id 与

Another try is use String as Primary key and set your id with

$entity->setId(new \DateTime()->format('yyyy/mm/dd'));

这是一个类似的问题： Symfony / Doctrine：DateTime作为主键

Here is a similar question: Symfony/Doctrine: DateTime as primary key

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