java - Spring Data 和 JPA 中的递归关系？

Question

我的 Comment 实体是自连接的，它有一个 subComment 集。

@Entity
public class Comment {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private String id;

@OneToMany(mappedBy = "parentComment", cascade = CascadeType.ALL)
private Set<Comment> subComments = new HashSet<>();

@ManyToOne
@JoinColumn(referencedColumnName = "id")
private Comment parentComment;

在我的addComment 方法中

public ResponseEntity<Comment> addComment(Comment comment) {
    Comment currComment = commentRepository.save(comment);
    if (currComment.getParentId() != null) {
        Comment parent = commentRepository.findById(currComment.getParentId()).orElse(null);
        if (parent != null) {
            parent.addSubComment(currComment);
            currComment.setParentId(parent.getId());
            currComment.setParentComment(parent);
            commentRepository.save(parent);
        }
    }
    Comment responseComment = commentRepository.save(currComment);
    return ResponseEntity.ok(responseComment);
}

当我试图建立反向关系(拥有方)时， comment.setParentComment(parent); 导致错误

comment.setParentComment(parent); 导致错误:java.lang.IllegalStateException: Cannot call sendError() after the response has been committed

完整评论实体类

@OneToMany(mappedBy = "parentComment", cascade = CascadeType.ALL)
private Set<Comment> subComments = new HashSet<>();

@ManyToOne
@JoinColumn(referencedColumnName = "id")
private Comment parentComment;

private boolean isParent;
private String parentId;

public String getParentId() {
    return parentId;
}

public void setParentId(String parentId) {
    this.parentId = parentId;
}

public Set<Comment> getSubComments() {
    return subComments;
}

public void setSubComments(Set<Comment> subComments) {
    this.subComments = subComments;
}

public Comment addSubComment(Comment comment) {
    this.subComments.add(comment);
    return this;
}

public Comment getParentComment() {
    return parentComment;
}

public void setParentComment(Comment parentComment) {
    this.parentComment = parentComment;
}

public boolean getIsParent() {
    return isParent;
}

public void setIsParent(boolean isParent) {
    this.isParent = isParent;
}

Answer 1

@ManyToOne
@JoinColumn(referencedColumnName = "id")
@JsonBackReference
private Comment parentComment;

我添加了 @JsonBackReference 解决了 java.lang.IllegalStateException: Cannot call sendError() after the response has been committed 错误。父 Comment 也可以看到 subComments 集。