mysql - 删除父级时续行孤儿移除

Question

我在 mysql 中有两个表:

create table comments
(
    id                 int unsigned auto_increment primary key,
    postId             varchar(100)                not null,
    text               text                        not null,
    constraint commentForPost foreign key (postId) references posts (id)
);

create table post
(
    id               varchar(100)                        not null primary key,
    name             varchar(100)                        not null,
);

以及 sequelize 中的以下两个模型:
post.js 文件:

class Post extends Model {}

Post.init({
    // Model attributes are defined here
    id: {
        type: DataTypes.STRING,
        primaryKey: true
    },
    name: {
        type: DataTypes.STRING,
    }
}, {
    // Other model options go here
    sequelize, // We need to pass the connection instance
    modelName: 'Post', // We need to choose the model name
    tableName: 'posts',
    timestamps: false
});


Post.hasMany(Comment, { foreignKey: 'postId', onDelete: 'CASCADE'})
Comment.belongsTo(Post, { foreignKey: 'postId' });

comment.js 文件:

class Comment extends Model {}
Comment.init({
    // Model attributes are defined here
    id: {
        type: DataTypes.STRING,
        primaryKey: true
    },
    postId: {
        type: DataTypes.STRING,
        allowNull: false
    },
    text: {
        type: DataTypes.text,
        allowNull: false
    }
}, {
    // Other model options go here
    sequelize, // We need to pass the connection instance
    modelName: 'Comment', // We need to choose the model name
    tableName: 'comments',
    timestamps: false
});

现在我想在删除帖子时删除帖子的评论。我正在使用的代码如下:

  const post = await Post.destroy({
    where: {id}
  });

这会生成以下查询:

DELETE FROM `posts` WHERE `id` = '1'

我得到的错误如下:

UnhandledPromiseRejectionWarning: SequelizeForeignKeyConstraintError: Cannot delete or update a parent row: a foreign key constraint fails (db.comments, CONSTRAINT commentForPost FOREIGN KEY (postId) REFERENCES posts (id))

我的 Sequelize 版本是: 6.3.5
如何实现删除帖子并删除“孤儿”评论？

Answer 1

您指定了 onDelete: 'CASCADE' 并且此选项将起作用，但仅适用于 sequelize.sync 调用(使用此选项创建外键)。通常的 destroy 调用不考虑这个选项。因此，您应该手动更改现有外键以设置 ON DELETE CASCADE 。