JPA：来自 SQL 脚本的级联应该反映在实体中吗？

Question

我有两个实体：course 和 category，它们由 @ManyToMany 注释关联。

@Entity
@Table(name = "categories")
public class Category {
    @Id
    @GeneratedValue(generator = "inc")
    @GenericGenerator(name = "inc", strategy = "increment")
    private int categoryId;
    private String name;

    @ManyToMany(cascade = CascadeType.PERSIST)
    @JoinTable(
            name="course_category",
            joinColumns = @JoinColumn(name = "category_id"),
            inverseJoinColumns = @JoinColumn(name = "course_id")
    )
    private Set<Course> courses;
}
@Entity
@Table(name = "courses")
public class Course {
    @Id
    @GeneratedValue(generator = "inc")
    @GenericGenerator(name = "inc", strategy = "increment")
    private int courseId;
    @NotBlank(message = "Add the course's title!")
    private String title;
    private String description;

    @ManyToMany(mappedBy = "courses")
    private Set<Category> categories;
}

我的目标是删除一个类别后，与该类别相关的课程不会被删除，只有关联必须被打破所以我在创建连接时包含了ON DELETE CASCADE table。

  CREATE TABLE course_category (
    category_id INT NOT NULL,
    course_id INT NOT NULL,
    FOREIGN KEY (category_id)
        REFERENCES categories(category_id)
        ON DELETE CASCADE,
    FOREIGN KEY (course_id)
        REFERENCES courses(course_id)
        ON DELETE CASCADE
    PRIMARY KEY (category_id, course_id)
)

如果我没记错的话，它应该可以实现我的目标。但现在我的问题是：我应该在我的实体中反映 ON DELETE CASCADE 吗？如果是这样，我该怎么做？通过添加 CascadeType.REMOVE?

Answer 1

您应该避免 on delete cascade 使用 JPA，因为那样的话数据库将删除可能仍存在于 JPA 持久性上下文中的行。

而是使用 CascadeType.REMOVE and/or orphanRemoval=true 级联 JPA 删除操作。

JPA：来自 SQL 脚本的级联应该反映在实体中吗？

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