hibernate - jpa实体不更新数据库中的关系操作

Question

我将组件对象映射到 componentMeta 对象，并且我设置了cascade(javax.persistence.CascadeType) action = all，但数据库中的关系操作仍然是Restrict(它没有更新为级联)

这里是组件对象:

@Entity
@Table(name = "component")
public class Component {

    private int                     idComponent;
    private List<ComponentMeta>     componentMetas;

    public Component() {
    }

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public int getIdComponent() {
        return this.idComponent;
    }

    public void setIdComponent(int idComponent) {
        this.idComponent = idComponent;
    }

    @OneToMany(mappedBy = "component", cascade = CascadeType.ALL)
    public List<ComponentMeta> getComponentMetas() {
        return this.componentMetas;
    }

    public void setComponentMetas(List<ComponentMeta> componentMetas) {
        this.componentMetas = componentMetas;
    }
}

和 ComponentMeta 对象:

@Entity
@Table(name = "ComponentMeta")
public class ComponentMeta {

    private int idComponentMeta;
    private Component component;

    public ComponentMeta() {
    }

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "idComponentMeta", unique = true, nullable = false)
    public int getIdComponentMeta() {
        return idComponentMeta;
    }

    public void setIdComponentMeta(int idComponentMeta) {
        this.idComponentMeta = idComponentMeta;
    }

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "idComponent")
    public Component getComponent() {
        return component;
    }

    public void setComponent(Component component) {
        this.component = component;
    }
}

数据库中有关系 Action 的图片(未更新为级联):

我在 Spring Boot 中的 hibernate 配置(application.properties):

spring.jpa.show-sql = true
spring.jpa.hibernate.ddl-auto = update
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

为什么关系操作不会自动更新为级联？

Answer 1

如果你想让hibernate在外键上生成ON DELETE CASCADE，你需要将@OnDelete放在@OneToMany一侧:

@OneToMany(mappedBy = "component", cascade = CascadeType.ALL)
@OnDelete(action = OnDeleteAction.CASCADE)