问题描述
我遵循并试图实现 9.4部分的示例。组件作为复合标识符但面临着如何实现它的问题。
以下是我所做的：
我的实体类：
Order.java
public class Order {
private int id;
私人套餐< OrderLine> lines = new HashSet< OrderLine>（）;
// Setters& Getters
OrderLine.java
public class OrderLine {
private OrderLineId id;
私人字符串名称;
私人订单;
// Setters& Getters
OrderLineId.java
public class OrderLineId implements Serializable {
private int lineId;
private int orderId;
private int customerId;
// Setters& Getters
}
我的映射文件存在问题：
< hibernate-mapping>
< class name =Ordertable =TEST_Order>
< id name =idtype =intcolumn =id>
< generator class =native/>
< / id>
< set name =linescascade =all>
< key column =orderId/>
<一对多等级=OrderLine/>
< / set>
< / class>
< class name =OrderLinetable =TEST_OrderLine>
< composite-id name =idclass =OrderLineId>
< key-property name =lineId/>
< key-property name =orderId/>
< key-property name =customerId/>
< / composite-id>
< property name =name/>
<多对一名称=orderclass =Order
insert =falseupdate =false>
< column name =orderId/>
< column name =customerId/>
< /多对一>
< / class>
< / hibernate-mapping>
当我试图创建解析这个映射文件的会话工厂时，我得到一个异常：
引起：org.hibernate.MappingException：外键（FK_89b4nqt5l2n6tfd1d5tq0ill0：TEST_OrderLine [orderId，customerId]））必须相同作为引用主键的列数（TEST_Order [id]）
在org.hibernate.mapping.ForeignKey.alignColumns（ForeignKey.java:110）
在org.hibernate.mapping.ForeignKey.alignColumns（ ForeignKey.java:93）
at org.hibernate.cfg.Configuration.secondPassCompileForeignKeys（Configuration.java:1816）
at org.hibernate.cfg.Configuration.originalSecondPassCompile（Configuration.java:1739）
at org.hibernate.cfg.Configuration.secondPassCompile（Configuration.java:1424）
at org.hibernate.cfg.Configuration.buildSessionFactory（Configuration.java:1844）
有人可以帮助我如何实现给出的示例
OrderLine需要引用Order PK，它不是一个复合键。
$ b
这意味着多对一必须是：
< many-to- one name =orderclass =Order
insert =falseupdate =false>
< column name =orderId/>
< /多对一>
orderId是Order.id的FK。
然后一对多一方将变成：
< set name =linescascade =所有>
< key>
< column name =orderId/>
< / key>
<一对多等级=OrderLine/>
< / set>
所以即使OrderLine有一个组合键，引用也是在Order.id之后进行的，是一个简单的键。
如果要将其他关联映射到OrderLine，如OrderLineProduct，则需要使用复合关键字来映射父关联（OrderLine）和子级（OrderLineProduct），以便OrderLineProduct将组合外键返回给OrderLine。
I am following Hibernate Documentation and trying to implement the example given for section 9.4. Components as composite identifiers but facing issues on how to implement it.
Here is what I have done:
My entity classes:
Order.java
public class Order {
private int id;
private Set<OrderLine> lines = new HashSet<OrderLine>();
// Setters & Getters
}
OrderLine.java
public class OrderLine {
private OrderLineId id;
private String name;
private Order order;
// Setters & Getters
}
OrderLineId.java
public class OrderLineId implements Serializable{
private int lineId;
private int orderId;
private int customerId;
// Setters & Getters
}
My mapping file which is having issues:
<hibernate-mapping>
<class name="Order" table="TEST_Order">
<id name="id" type="int" column="id">
<generator class="native"/>
</id>
<set name="lines" cascade="all">
<key column="orderId"/>
<one-to-many class="OrderLine"/>
</set>
</class>
<class name="OrderLine" table="TEST_OrderLine">
<composite-id name="id" class="OrderLineId">
<key-property name="lineId"/>
<key-property name="orderId"/>
<key-property name="customerId"/>
</composite-id>
<property name="name"/>
<many-to-one name="order" class="Order"
insert="false" update="false">
<column name="orderId"/>
<column name="customerId"/>
</many-to-one>
</class>
</hibernate-mapping>
When I am trying to create a session factory which parses this mapping file, I am getting an exception saying:
Caused by: org.hibernate.MappingException: Foreign key (FK_89b4nqt5l2n6tfd1d5tq0ill0:TEST_OrderLine [orderId,customerId])) must have same number of columns as the referenced primary key (TEST_Order [id])
at org.hibernate.mapping.ForeignKey.alignColumns(ForeignKey.java:110)
at org.hibernate.mapping.ForeignKey.alignColumns(ForeignKey.java:93)
at org.hibernate.cfg.Configuration.secondPassCompileForeignKeys(Configuration.java:1816)
at org.hibernate.cfg.Configuration.originalSecondPassCompile(Configuration.java:1739)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1424)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1844)
Can someone please help me how to implement the example given in the documentation.
The OrderLine needs to refernece the Order PK, which is not a composite key.
It means the many-to-one must be:
<many-to-one name="order" class="Order"
insert="false" update="false">
<column name="orderId"/>
</many-to-one>
The orderId is the FK to Order.id.
Then the one-to-many side will become:
<set name="lines" cascade="all">
<key>
<column name="orderId"/>
</key>
<one-to-many class="OrderLine"/>
</set>
So even if the OrderLine has a composite-key, the reference is made after Order.id, which is a simple key.
If you want to map other association to OrderLine, like OrderLineProduct then you'll need to use the composite-key to map the association between the parent (OrderLine) and the child (OrderLineProduct), so that OrderLineProduct has a composite-foreign-key back to OrderLine.
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