Cascade.Type = ALL 在尝试删除自己的行之前不会删除所有“子行”

Question

我正在尝试删除一个用户，但在 hibernate 尝试删除该用户之前，数据库中引用该用户的每一行都不会被删除。

我对应用程序中的每个其他实体都有相同的结构，它工作得很好，首先删除所有子行，然后删除行本身，但正如您在下面看到的那样，尝试删除时并非如此一个用户。 Hibernate 走到这一步：

Hibernate: delete from users where user_id=?

在所有评论投票被删除之前。 （之前也应该删除帖子，但我猜comment_votes错误首先出现）。

根据控制台报错前执行这一系列sql语句：

Hibernate: delete from comment_vote where vote_id=?
Hibernate: delete from comment where comment_id=?
Hibernate: delete from comment_vote where vote_id=?
Hibernate: delete from comment where comment_id=?
Hibernate: delete from comment_vote where vote_id=?
Hibernate: delete from comment where comment_id=?
Hibernate: delete from users where user_id=?

这是我得到的错误：

org.postgresql.util.PSQLException: ERROR: update or delete on table "users" violates foreign key constraint "fkjf73ixvt1jv3wdv4ah0hkpewf" on table "comment_vote"
  Detail: Key (user_id)=(2) is still referenced from table "comment_vote".

用户.java：

@Entity
@Table(name = "users") // because User is a keyword in some DBs
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "user_id", columnDefinition = "serial")
    private Long id;

    @NotEmpty
    @Column(unique = true)
    private String username;

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    @JsonIgnore
    private List<Post> posts = new ArrayList<>();

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    @JsonIgnore
    private List<Comment> comments = new ArrayList<>();

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    @JsonIgnore
    private List<CommentVote> comment_votes = new ArrayList<>();

    @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
    @JsonIgnore
    private List<PostVote> post_votes = new ArrayList<>();

    // getters and setters
}

这是 CommentVote.java ：

@Entity
@Table(name = "comment_vote")
public class CommentVote {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "vote_id", columnDefinition = "serial")
    private Long id;

    @Min(value = -1, message = "A vote can not be less than -1")
    @Max(value = 1, message = "A vote can not be greater than 1")
    @Column(name = "actual_vote")
    private int actualVote;

    @ManyToOne()
    @JoinColumn(name="user_id", nullable=false)
    @JsonIgnore
    private User user;

    // getters and setters
}

我尝试在 User.java 中的每个子字段上使用 orphanRemoval = true 但这似乎没有任何改变。

Answer 1

您可以尝试使用@OnDelete。正如documentation 中所述：

...@OnDelete 级联是 DDL 级别的 FK 功能，它允许您在删除父行时删除子记录。

因此，当注释 @ManyToOne 与 @OnDelete(action = OnDeleteAction.CASCADE) 关联时，自动架构生成器会将 ON DELETE CASCADE SQL 指令应用于外键声明。

考虑到这一点，您可以通过以下方式更正您的映射：

@Entity
@Table(name = "comment_vote")
public class CommentVote {

    // ...

    @ManyToOne()
    @JoinColumn(name="user_id", nullable=false)
    @OnDelete(action = OnDeleteAction.CASCADE)
    @JsonIgnore
    private User user;

    // ...
}