在 JPA、Hibernate 中连接 2 个带有非键列的表

Question

我正在使用具有 tables skl_transactions 和 merchant_config 的遗留数据库。这两个 tables 有一个列，其中它们的值彼此相等（例如 skl_transactions.column_a === merchant_config.column.b 。我正在寻找一种方法来加入两个 tables基于该公共值而不是查询数据库两次。

看看我的想法，但我总是出错

(" => "org.hibernate.MappingException: Unable to find column with logical name: column_a in org.hibernate.mapping.Table(merchant_config) and its related supertables and secondary tables
    Caused by: org.hibernate.MappingException: Unable to find column with logical name: column_a in org.hibernate.mapping.Table(merchant_config) and its related supertables and secondary tables"}}

下面是我的实体class

@Entity
@Table(name = "skl_transactions")
public class Foo implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Basic(optional = false)
    protected Long id;

    @Column(name = "column_a")
    private String senderAddress;

    -----

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="column_b", referencedColumnName = "column_a")
    private Bar merchant;

    // getters and setters
}

@Entity
@Table(name = "merchant_config")
public class Bar implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Basic(optional = false)
    protected Long id;

    @Column(name = "column_b")
    private String merchantAddress;

    -----

    @OneToMany(mappedBy = "merchant_config", fetch = FetchType.LAZY)
    private List<Foo> transactions = new ArrayList<>();

    // getters and setters
}

注意：两列都未标记为主键或外键。

我正在寻找的是当我从 skl_transactions table 查询交易时，它会加入从 merchant_config table 进行交易的商家。

Answer 1

您需要将 mappedBy 更改为 merchant

Foo

@Entity
@Table(name = "skl_transactions")
public class Foo implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Basic(optional = false)
    protected Long id;

    @Column(name = "column_a")
    private String senderAddress;

    -----

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="column_b", referencedColumnName = "column_a", insertable=false, updatable=false)
    private Bar merchant;

    // getters and setters
}

栏

@Entity
@Table(name = "merchant_config")
public class Bar implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Basic(optional = false)
    protected Long id;

    @Column(name = "column_b")
    private String merchantAddress;

    -----

    @OneToMany(mappedBy = "merchant", fetch = FetchType.LAZY)
    private List<Foo> transactions = new ArrayList<>();

    // getters and setters
}

如果以上有任何问题，请尝试将 name 和 referencedColumnName 反过来

in Foo
@ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="column_a", referencedColumnName = "column_b", insertable=false, updatable=false)
    private Bar merchant;

in Bar
@OneToMany(mappedBy = "merchant", fetch = FetchType.LAZY)
    private List<Foo> transactions = new ArrayList<>();

在 JPA、Hibernate 中连接 2 个带有非键列的表

Joining 2 tables with non-key columns in JPA, Hibernate

java

mysql

hibernate

java-ee-7

java-ee-8