Hibernate单表继承 [英] Hibernate Single Table Inheritance

问题描述

我有两个实体BillingAddress和ShippingAddress映射到具有鉴别器TYPE列的TABLE ADDRESS。

  @Entity 
 @Table（name =address）
 @Inheritance（strategy = InheritanceType。 SINGLE_TABLE）
 @DiscriminatorColumn（name =TYPE，discriminatorType = DiscriminatorType.INTEGER）
 @DiscriminatorValue（value =1）
 @NamedQueries（{
 @NamedQuery =Shippingaddress.findAll，query =SELECT s FROM Shippingaddress s）} 
 public class Shippingaddress implements Serializable {} 
 $ b @Entity 
 @Table（name =地址）
 @DiscriminatorValue（value =2）
 @NamedQueries（{
 @NamedQuery（name =Billingaddress.findAll，query =SELECT b FROM Billingaddress b）} ）
 public class Billingaddress extends Shippingaddress implements Serializable {} 
  

我可以保存/更新这两个地址类型成功地在数据库中使用不同的TYPE值。

我遇到的问题是当我查询ADDRESS表时，如下所示：

  Session session = getCurrentSession（ ）; 
 Query query = session.createQuery（from Billingaddress where userId.userId =：userId）; 
 query.setLong（userId，userId）; 
 billingaddress =（Billingaddress）query.uniqueResult（）; 
  

这工作正常，但是查询ShippingAddress会抛出NonUniqueResult异常，即我得到Shippingaddress和Billingaddress。请让我知道，我该怎么做不同。

  Session session = getCurrentSession（）; 
 Query query = session.createQuery（from Shippingaddress where userId.userId =：userId）; 
 query.setLong（userId，userId）; 
 shippingaddress =（Shippingaddress）query.uniqueResult（）; 
  

解决方案

另一个解决方案是创建一个抽象类Address和map父类中具有insertable = false，updatable = false的列

然后，您可以在查询中添加该类型：

  @Entity 
 @Table（name =address）
 @Inheritance（strategy = InheritanceType.SINGLE_TABLE）
 @DiscriminatorColumn name =TYPE，discriminatorType = DiscriminatorType.INTEGER）
 @NamedQueries（{
 @NamedQuery（name =Address.findAll，query =SELECT s FROM Address s where type =：type） }）
 public class Address implements Serializable {
 @Column（name =TYPE，insertable = false，updatable = false）
 private Integer type; 
 
 
 @Entity 
 @DiscriminatorValue（value =1）
 @NamedQueries（{
 @NamedQuery（name =Shippingaddress.findAll ，query =SELECT s FROM Shippingaddress s）} 
 public class Shippingaddress implements Serializable {} 
 $ b @Entity 
 @DiscriminatorValue（value =2）
 @NamedQueries（{
 @NamedQuery（name =Billingaddress.findAll，query =SELECT b FROM Billingaddress b）}）
 public class Billingaddress extends Shippingaddress implements Serializable {} 
  

然后您可以写入from Address where type = 1与from Shippingaddress和from Address相同检索所有行

I have two Entities BillingAddress and ShippingAddress mapped to TABLE ADDRESS having discriminator TYPE column.

@Entity
@Table(name = "address")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "TYPE",discriminatorType = DiscriminatorType.INTEGER)
@DiscriminatorValue(value = "1")
@NamedQueries({
    @NamedQuery(name = "Shippingaddress.findAll", query = "SELECT s FROM Shippingaddress s")})
public class Shippingaddress  implements Serializable{}

@Entity
@Table(name = "address")
@DiscriminatorValue(value = "2")
@NamedQueries({
    @NamedQuery(name = "Billingaddress.findAll", query = "SELECT b FROM Billingaddress b")})
public class Billingaddress extends Shippingaddress implements Serializable {}

I am able to save/update the two address type successfully in DB with different TYPE values.

The problem I am facing is when I am querying ADDRESS table as follows:

Session session=getCurrentSession();
        Query query=session.createQuery("from Billingaddress where userId.userId=:userId");
        query.setLong("userId", userId);
        billingaddress=(Billingaddress)query.uniqueResult();

This works fine , but querying ShippingAddress throws NonUniqueResult Exception ie I get both Shippingaddress and Billingaddress in result. Please let me know , what should I do differently.

Session session=getCurrentSession();
        Query query=session.createQuery("from Shippingaddress where userId.userId=:userId");
        query.setLong("userId", userId);
        shippingaddress=(Shippingaddress)query.uniqueResult();

解决方案

another solution is to create an abstract class Address and map the column in the parent class with "insertable = false, updatable = false"

Then you can add the type in your query:

@Entity
@Table(name = "address")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "TYPE",discriminatorType = DiscriminatorType.INTEGER)
@NamedQueries({
@NamedQuery(name = "Address.findAll", query = "SELECT s FROM Address s where type = :type")})
public class Address implements Serializable {
    @Column(name="TYPE", insertable=false, updatable=false)
    private Integer type;
}

@Entity
@DiscriminatorValue(value = "1")
@NamedQueries({
@NamedQuery(name = "Shippingaddress.findAll", query = "SELECT s FROM Shippingaddress s")})
public class Shippingaddress  implements Serializable{}

@Entity
@DiscriminatorValue(value = "2")
@NamedQueries({
@NamedQuery(name = "Billingaddress.findAll", query = "SELECT b FROM Billingaddress b")})
public class Billingaddress extends Shippingaddress implements Serializable {}

then you can write "from Address where type = 1" is the same as "from Shippingaddress" and "from Address" will retrieve all rows

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