带有对象引用的JPA复合键 [英] JPA Composite Key with Object references

问题描述

在创建带有对象引用的JPA复合密钥时，我遇到了一些问题。实体如下所示，

I have faced some issue while creating JPA Composite Key with Object references. Entities are as show in bellow,

1）我想从Workflow实体中删除 ID 字段，并结合使用 > seqNo 字段和 template （对象引用）字段

1) I wan to remove the ID field from Workflow entity and make a composite key with combining seqNo field and template (object reference) field

2）根据该更改，将现有关系更新为命令实体（@JoinColumn（名称= WORKFLOW_ID，referencedColumnName = ID））

2) According to that change updated the existing relationship with Command entity (@JoinColumn(name = "WORKFLOW_ID", referencedColumnName = "ID"))

谢谢。

模板实体：

@Entity
@Table(name = "template")
public class Template implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @SequenceGenerator(name="template_se", sequenceName="TEMPLATE_SE", allocationSize=1, initialValue=1)
    @Basic(optional = false)
    @Column(name = "ID")
    private Integer id;

    @Basic(optional = false)
    @Column(name = "NAME", unique = true)
    private String name;

    @OneToMany(cascade = CascadeType.REMOVE, mappedBy = "template")
    @LazyCollection(LazyCollectionOption.FALSE)
    private List<Workflow> workflowList;
}

工作流程实体：

@Entity
@Table(name = "workflow")
public class Workflow implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @SequenceGenerator(name="wf_se", sequenceName="WF_SE", allocationSize=1, initialValue=1)
    @Basic(optional = false)
    @Column(name = "ID")
    private Integer id;

    @Basic(optional = false)
    @Column(name = "SEQ_NO")
    private int seqNo;

    @JoinColumn(name = "T_ID", referencedColumnName = "ID", nullable = false)
    @ManyToOne
    private Template template;

    @Basic(optional = false)
    @Column(name = "NAME")
    private String name;
}

命令实体：

@Entity
@Table(name = "command")
public class Command implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @SequenceGenerator(name="command_se", sequenceName="COMMAND_SE", allocationSize=1, initialValue=1)
    @Basic(optional = false)
    @Column(name = "ID")
    private Integer id;

    @JoinColumn(name = "WORKFLOW_ID", referencedColumnName = "ID")
    @ManyToOne(optional = false)
    private Workflow workflow;
} 

推荐答案

我已经把事情做好了

EmbeddedId类

@Embeddable
public class WorkflowPK implements Serializable {

    @Basic(optional = false)
    @Column(name = "SEQ_NO")
    private int seqNo;

    @JoinColumn(name = "T_ID", referencedColumnName = "ID", nullable = false)
    @ManyToOne
    private Template template;
} 

工作流实体（带有EmbeddedId）

Workflow Entity (with EmbeddedId)

@Entity
@Table(name = "workflow")
public class Workflow implements Serializable {

    @EmbeddedId
    private WorkflowPK id;

    @Basic(optional = false)
    @Column(name = "NAME")
    private String name;
}

模板实体具有双向关系

@Entity
@Table(name = "template")
public class Template implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @SequenceGenerator(name="template_se", sequenceName="TEMPLATE_SE", allocationSize=1, initialValue=1)
    @Basic(optional = false)
    @Column(name = "ID")
    private Integer id;

    @Basic(optional = false)
    @Column(name = "NAME", unique = true)
    private String name;

    // Refer the filed "template" inside the Composite key of Workflow entity

    @OneToMany(cascade = CascadeType.REMOVE, mappedBy = "id.template")
    @LazyCollection(LazyCollectionOption.FALSE)
    @OrderBy(value = "id.stepSeqNo")
    private List<Workflow> workflowList;
} 

命令实体，其中JoinColumn参考

Command entity with JoinColumn reference

@Entity
@Table(name = "command")
public class Command implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    @SequenceGenerator(name="command_se", sequenceName="COMMAND_SE", allocationSize=1, initialValue=1)
    @Basic(optional = false)
    @Column(name = "ID")
    private Integer id;

    // Refer the Composite key of Workflow entity

    @ManyToOne(optional = false)
    @JoinColumns ({
            @JoinColumn(name="WORKFLOW_SEQ_NO_ID", referencedColumnName = "SEQ_NO"),
            @JoinColumn(name="WORKFLOW_T_ID", referencedColumnName = "T_ID"),
    })
    private WorkflowStep workflow;
} 

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