JPA 带前缀的多个嵌入式字段？

Question

使用 JPA 注释，我想像这样重用相同的嵌入式 object：

@Entity
public class User {
    @Embedded
    public Address homeAddress;

    @Embedded
    public Address workAddress;
}

@Embeddable
public class Address {
    public String code;
    public String city;
    ...
} 

我可以使用 @AttributeOverrides、@AttributeOverride 和 @Column 指定 SQL 列名称，但它是冗长的。 是否可以只指定一个前缀添加到 homeAddress 和 workAddress 的每一列？

谢谢，

泽维尔

Answer 1

如果您想使用多个相同的Embedded类。 您必须为所有列执行@AttributeOverrides 。 试试如下;

参考JPA AttributeOverrides

@Embeddable
public class Address {
    private String state;
    @Column(name = "zip_code")
    private String zip;
}

@Entity(name = "Employee")
public class Employee implements Serializable {
    @Embedded
    @AttributeOverrides({
        @AttributeOverride(name = "state", column = @Column(name = "province_1")),                       
        @AttributeOverride(name = "zip", column = @Column(name = "postal_code_2"))
    })
    private Address address_1;  

    @Embedded
    @AttributeOverrides({
        @AttributeOverride(name = "state", column = @Column(name = "province_2")),                       
        @AttributeOverride(name = "zip", column = @Column(name = "postal_code_2"))
    })
    private Address address_2;  

}   

我的建议，如果您的Entity有一个或多个Embedded值。 尝试使用@CollectionTable 。

@CollectionTable(name = "EMPLOYEE_ADDRESS", joinColumns = @JoinColumn(name = "ADDRESS_ID"))
private List<Address> addressList;

参考JPA CollectionTable

Answer 2

添加这个对我有用（虽然我使用 hibernate 作为 JPA 提供商）

<property name="hibernate.implicit_naming_strategy" value="org.hibernate.boot.model.naming.ImplicitNamingStrategyComponentPathImpl" />

Answer 3

有同样的问题，这是解决方案。 完美的工作，前缀字段名称与嵌入属性的名称（在您的情况下homeAddress_和workAddress_）

https://stackoverflow.com/a/3046725/4252764

Answer 4

2022 年（9 年后）@zaw-than-oo -s 的回答仍然有效：-(。

如果有人想改进 jpa-embedded，此“重复”答案仅供参考。

这是一个基于@zaw-than-oo -s 答案的工作跨平台示例，带有详细的 java-jpa 和易于使用的 android-room

@androidx.room.Entity
@javax.persistence.Entity
@javax.persistence.Inheritance(strategy = javax.persistence.InheritanceType.SINGLE_TABLE)
public class AppHardware {
    @javax.persistence.Id
    @javax.persistence.GeneratedValue(strategy = javax.persistence.GenerationType.AUTO)
    @androidx.room.PrimaryKey(autoGenerate = true)
    private int id;

    // max is embedded without column renaming
    @androidx.room.Embedded
    @javax.persistence.Embedded
    private ProfileCommon max;

    // min is embedded with column renaming
    @androidx.room.Embedded(prefix = "min")
    @javax.persistence.Embedded
    @javax.persistence.AttributeOverrides({
        // Verbose: every persisted property in ProfileCommon needs an entry
        // see https://stackoverflow.com/questions/12912063/jpa-multiple-embedded-fields-with-prefix
        @AttributeOverride(name = "added", column = @Column(name = "minadded")),
        @AttributeOverride(name = "apkName", column = @Column(name = "minapkName")),
        @AttributeOverride(name = "versionCode", column = @Column(name = "minversionCode")),
        @AttributeOverride(name = "versionName", column = @Column(name = "minversionName")),
        @AttributeOverride(name = "size", column = @Column(name = "minsize"))
        
    })
    private ProfileCommon min;

    // getter and setter onmitted
}

@javax.persistence.MappedSuperclass
public class ProfileCommon  {
    private long added; // date
    private String apkName;
    private long versionCode;
    private String versionName;
    private long size;

// getter and setter onmitted
}