Grails GORM：我如何创建一个复合主键并将其用于表关系？ [英] Grails GORM: How do I create a composite primary key and use it for a table relationship?

问题描述

我有两个表，其中一个表（旧表：A）有两个字段应该用作复合外键，另一个表（新表：B）应该为<$ c $使用复合主键c>每一行：A有一行：B 关系。我如何用GORM来描述这些表？

到目前为止，我已经能够创建一个反映遗留表的域类：A

  class A {
 
 ... 
 //复合外键链接B class 
 String className; 
字符串eventName; 
 
 B b; // B的实例关联
 
 static mapping = {
 table'a_table'; 
 id列：'id'; 
 className列：'class_name'; 
 eventName列：'event_name'; 
 // b：??? 
 
 
 $ / code $ / pre 
 
 
可以工作，但我无法创建 new class：B 和关系。
 
 
 
我试图将B声明为： 
 
 
  class B实现了Serializable {
 
 static auditable = true; 
 
字符串名称; 
 String className; 
字符串eventName; 
 
 static mapping = {
 //假设要创建一个复合PK 
 id复合：[className，eventName] 
} 
} 
  
但这不会使用
 
  ERROR context.GrailsContextLoader进行编译 - 执行引导时出错：为域[com.package.B]计算ORM映射块时出错：没有这样的属性：类名为eventName：org.codehaus.groovy.grails.orm.hibernate.cfg.HibernateMappingBuilder  
 
 
 
我想要的是这样的： 
 
 
  static mapping = { 
 ... 
b复合：[b.className：className，b.eventName：eventName] 
 //或者其他任何方法都可以完成。 
} 
  
为A类使GORM处理这种关系。
解决方案
您是否尝试使用属性名称而不是使用属性值？ 
 
 
 类B实现Serializable {
字符串名称; 
 String className; 
字符串eventName; 
 
静态映射= {
 //应该创建一个复合PK 
 id复合：['className'，'eventName'] 
} 
} 
  
和A中的映射： 
 
 
  class A {
 static hasMany = [b：B] 
} 
  
在 A 中不需要有 className 或 eventName  code> 
 
I have two tables, one of which (legacy table: A) has two fields that should serve as a composite foreign key and the other one (new table: B) should use a composite primary key for a each row:A has one row:B relationship. How do I describe these tables in terms of GORM?

So far I've been able to create a domain class that reflects the legacy table:A
class A {

    ...
    //composite foreign key to link B class
    String className;
    String eventName;

    B b; //instance of B to be related

    static mapping = {
        table 'a_table';            
        id column: 'id';
        className column: 'class_name';
        eventName column: 'event_name';
        //b: ???
    }
}
which works, but I can't create a new class:B and the relationship.

I tried to declare B as:
class B implements Serializable{

    static auditable = true;

    String name;
    String className;
    String eventName;

    static mapping = {
        //supposed to make a composite PK
        id composite:[className, eventName] 
    }
}
but this won't compile with a

ERROR context.GrailsContextLoader  - Error executing bootstraps: Error evaluating ORM mappings block for domain [com.package.B]:  No such property: eventName for class: org.codehaus.groovy.grails.orm.hibernate.cfg.HibernateMappingBuilder

What I want is something like:
static mapping = {
    ...
    b composite: [b.className:className, b.eventName:eventName]
    //or whatever is the right way for this to be done.
}
for the A class to make GORM handle this relation.
解决方案
Did you try to use attribute name instead of use attribute value ?
class B implements Serializable{
    String name;
    String className;
    String eventName;

    static mapping = {
        //supposed to make a composite PK
        id composite:['className', 'eventName'] 
    }
}
And mapping in A :
class A {
    static hasMany = [ b : B ]
}
No need to have className or eventName in A

                        
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