TypeORM/MySQL：无法删除或更新父行：外键约束失败

Posted 2023-02-24

【中文标题】TypeORM/MySQL：无法删除或更新父行：外键约束失败

【英文标题】：TypeORM/MySQL: Cannot delete or update a parent row: a foreign key constraint fails

【发布时间】：2021-11-13 11:58:17

【问题描述】：

我在comments 和posts 之间有实体关系_many-to-one_。我正在使用typeorm 和typegraphql

这是我的帖子实体：

@ObjectType()
@Entity()
export class Post extends BaseEntity 
  constructor(input: InputI) 
    super();
    this.caption = input?.caption;
    this.imageURL = input?.imageURL;
    this.status = input?.status;
    this.user = input?.user;
  

  @Field(() => Int)
  @PrimaryGeneratedColumn( type: "int" )
  id: number;

  @Field(() => String,  nullable: true )
  @Column( type: "text", nullable: true )
  caption?: string;

  @Field(() => String,  nullable: true )
  @Column( type: "text", nullable: true )
  imageURL?: string;

  @Field(() => String,  nullable: true )
  @Column( type: "text", nullable: true )
  status?: string;

  // Relations
  @Field(() => User)
  @ManyToOne(() => User, (user) => user.posts)
  user: User;

  @Field(() => [Comments],  nullable: true )
  @OneToMany(() => Comments, (comment) => comment.post, 
    onDelete: "CASCADE",
    onUpdate: "CASCADE",
  )
  comments: Comments[];

  @Field(() => [Likes],  nullable: true )
  @OneToMany(() => Likes, (like) => like.post, 
    onDelete: "CASCADE",
    onUpdate: "CASCADE",
  )
  likes: Likes[];

  @Field(() => String)
  @CreateDateColumn( nullable: false )
  createdAt: Date;
  
  @Field(() => String)
  @UpdateDateColumn( nullable: false )
  updatedAt: Date;

这是我的评论实体：

@ObjectType()
@Entity()
export class Comments extends BaseEntity 
  @Field(() => Int)
  @PrimaryGeneratedColumn( type: "int" )
  id: number;

  @Field(() => String)
  @Column( nullable: true )
  avatar: string;

  @Field(() => String)
  @Column( nullable: false )
  comment: string;

  @Field(() => String)
  @Column( nullable: false )
  email: string;

  @Field(() => String)
  @Column( nullable: false )
  username: string;

  @Field(() => String)
  @Column( nullable: true )
  phoneNumber: string;

  @Field(() => String)
  @Column( nullable: false )
  gender: string;

  @Field(() => String)
  @Column( nullable: false )
  status: string;

  @Field(() => String)
  @Column( nullable: true, type: "text" )
  bio: string;

  @Field(() => Boolean)
  @Column( nullable: false, default: false )
  verified: false | true;
  // @Field(() => [Comments],  nullable: true )
  // @OneToMany(() => Comments, (comment) => comment)
  // @JoinColumn()
  // replies: Comments[];
  //  @ManyToOne(() => Post, (post) => post.likes)
  // post: Post;

  @ManyToOne(() => Post, (post) => post.comments)
  post: Post;
  //
  @Field(() => String)
  @CreateDateColumn( type: "datetime", nullable: false )
  createdAt: Date;

  @Field(() => String)
  @UpdateDateColumn( type: "datetime", nullable: false )
  updatedAt: Date;

我对其他突变没有任何问题，唯一的问题是我想删除一个帖子。我在 GraphQLPlayGround 中收到以下错误：

"errors": [
    
      "message": "Cannot delete or update a parent row: a foreign key constraint fails (`likeme`.`comments`, CONSTRAINT `FK_e44ddaaa6d058cb4092f83ad61f` FOREIGN KEY (`postId`) REFERENCES `post` (`id`))",
...

这是我删除帖子的解析器。

@Resolver()
export class DeletePostResolver 
  @Mutation(() => Boolean)
  async deletePost(
    @Arg("id", () => Int) id: number,
    @Ctx()  req : UserContext
  ): Promise<Boolean> 
    const post = await Post.findOne(
       id ,
       relations: ["user", "comments", "likes"] 
    );
    if (post?.user.id === req.session.userId) 
      await Post.delete( id );
      return true;
    
    return false;
  

我的问题可能是什么，我已将 onDelete 设置为 CASCADE 那么这里有什么问题？ 请帮忙。

【参考方案1】：

您需要在Comment 实体中为post 列设置onDelete。 删除Post实体时，Comment实体中的post列需要解析关系引用，但onDelete未设置post列，则查询无法运行。

评论实体：

@ObjectType()
@Entity()
export class Comments extends BaseEntity 
  @Field(() => Int)
  @PrimaryGeneratedColumn( type: "int" )
  id: number;

  @Field(() => String)
  @Column( nullable: true )
  avatar: string;

  @Field(() => String)
  @Column( nullable: false )
  comment: string;

  @Field(() => String)
  @Column( nullable: false )
  email: string;

  @Field(() => String)
  @Column( nullable: false )
  username: string;

  @Field(() => String)
  @Column( nullable: true )
  phoneNumber: string;

  @Field(() => String)
  @Column( nullable: false )
  gender: string;

  @Field(() => String)
  @Column( nullable: false )
  status: string;

  @Field(() => String)
  @Column( nullable: true, type: "text" )
  bio: string;

  @Field(() => Boolean)
  @Column( nullable: false, default: false )
  verified: false | true;
  // @Field(() => [Comments],  nullable: true )
  // @OneToMany(() => Comments, (comment) => comment)
  // @JoinColumn()
  // replies: Comments[];
  //  @ManyToOne(() => Post, (post) => post.likes)
  // post: Post;

  @ManyToOne(() => Post, (post) => post.comments, 
    onDelete: "CASCADE", // <---- HERE
  )
  post: Post;
  //
  @Field(() => String)
  @CreateDateColumn( type: "datetime", nullable: false )
  createdAt: Date;

  @Field(() => String)
  @UpdateDateColumn( type: "datetime", nullable: false )
  updatedAt: Date;