Question

我想为3个域类创建3个单独的表：A，B扩展A，C扩展B 但我希望他们的桌子不相互连接。

在hibernate中，我会在grails中使用InheritanceType.TABLE_PER_CLASS，它会等同于什么？

Answer 1

尝试使用 tablePerHierarchy false

class Payment {
    Integer amount
    static mapping = {
        tablePerHierarchy false
    }
}

class CreditCardPayment extends Payment {
    String cardNumber
}

查看更多：http://grails.org/doc/latest/guide/single.html#5.5.2.3%20Inheritance%20Strategies

Answer 2

我试图实现的东西，是的，有可能用grails，这是一个弯曲勺子一点实现它：

在grails 3下执行此操作

您有一个您希望扩展的基类，并且具有相同字段的子表，即TABLE_PER_CLASS：

我发现了另一个有帮助的帖子，但有一条评论，但现在在这篇文章中正确扩展和解释：

这可能是我们的基础域类，但它不是在grails-app/domains/中创建的，而是在src/main/groovy/test下创建的

package test

abstract class Tester {
    String name
    String something

    static mapping = {
        tablePerConcreteClass true
        id generator: 'increment'
        version false
    }
}

接下来是grails-app/domains/test中的实际域类：

package  test
class Tester1 extends Tester {
}

和

package  test
class Tester2 extends Tester {
}

看着mysql：

mysql> show create table tester2;
+---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table   | Create Table                                                                                                                                                                                                                                                            |
+---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tester2 | CREATE TABLE `tester2` (
  `id` bigint(20) NOT NULL,
  `something` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  `name` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci |
+---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> show create table tester1;
+---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table   | Create Table                                                                                                                                                                                                                                                            |
+---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tester1 | CREATE TABLE `tester1` (
  `id` bigint(20) NOT NULL,
  `something` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  `name` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci |
+---------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

相当于Grails中的InheritanceType.TABLE_PER_CLASS？

2 个答案: