防止在映射表中创建外键？

Question

我们如何防止在休眠中创建外键？我需要在我的“oneToMany”关系中插入一些尚不存在的孩子。 Hibernate 应该忽略孩子还不存在的事实。

目前，一旦我尝试插入那些不存在的子项，我就会收到一个外键异常。所以我需要禁用外键 creation/useage.

@Entity
@Table(name = "chunk", uniqueConstraints = {@UniqueConstraint(columnNames={"x", "y"})}, indexes = {@Index(columnList = "x,y")})
@Access(value = AccessType.FIELD)
@SelectBeforeUpdate(false)
public class Chunk extends HibernateComponent{

    public int x;
    public int y;
    public Date createdOn;

    @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @Fetch(FetchMode.JOIN)
    @BatchSize(size = 50)
    public Set<Identity> inChunk = new LinkedHashSet<>();

    @Transient
    public Set<ChunkLoader> loadedBy = new LinkedHashSet<>();

    public Chunk() {}
    public Chunk(int x, int y, Date createdOn) {
        this.x = x;
        this.y = y;
        this.createdOn = createdOn;
    }
}

我们如何实现这一点？

Answer 1

我找到了一个解决方案...而不是让 Hibernate 自己完全创建连接 table 您可以使用“JoinTable”修改创建。

@Entity
@Table(name = "chunk", uniqueConstraints = {@UniqueConstraint(columnNames={"x", "y"})}, indexes = {@Index(columnList = "x,y")})
@Access(value = AccessType.FIELD)
@SelectBeforeUpdate(false)
public class Chunk extends HibernateComponent{

    public int x;
    public int y;
    public Date createdOn;

    @OneToMany(fetch = FetchType.EAGER, cascade = {})
    @JoinTable(name = "chunk_identity", joinColumns = @JoinColumn(name = "identity_id"), inverseJoinColumns = @JoinColumn(name = "id"), inverseForeignKey = @ForeignKey(ConstraintMode.NO_CONSTRAINT))
    @Fetch(FetchMode.JOIN)
    @BatchSize(size = 50)
    public Set<Identity> inChunk = new LinkedHashSet<>();

    @Transient
    public Set<ChunkLoader> loadedBy = new LinkedHashSet<>();

    public Chunk() {}
    public Chunk(int x, int y, Date createdOn) {
        this.x = x;
        this.y = y;
        this.createdOn = createdOn;
    }
}

这样我们就可以定义我们是否需要外键或者我们是否可以简单地忽略它。

防止在映射表中创建外键？

Prevent creation of foreign keys in mapping tables?

java

hibernate

jpa

hibernate-mapping