无法使用 belongsToMany 正确使用多对多

Question

一段时间以来，我一直在努力解决这个问题。我读到 hasMany 在尝试建立 many-to-many 关联时不是正确的方法。我有两个表来创建以下关联 User 和 Follower（现在这个名字很糟糕）。

追随者

const follower = (sequelize, DataTypes) => {
  const Follower = sequelize.define('follower', {
    follower_id: {
        type: DataTypes.INTEGER,
        allowNull: false,
        validate: {
            notNull: true
        }
    },
    following_id: {
        type: DataTypes.INTEGER,
        allowNull: false,
        validate: {
            notNull: true
        }
    }
  });

  return Follower;
};

module.exports = follower;

接下来我们将用户模型设为

const user = (sequelize, DataTypes) => {
  const User = sequelize.define('user', {
      email: {
        type: DataTypes.STRING,
        unique: true,
        allowNull: false,
        validate: {
            isEmail: true,
            notEmpty: true
        }
      },
      password: {
        type: DataTypes.STRING,
        allowNull: false,
        validate: {
            notEmpty: true
        }
      },
      username: {
        type: DataTypes.STRING,
        unique: true,
        allowNull: false
      }
  });

  User.associate = (models) => {
    User.hasMany(models.post, { foreignKey: 'user_id' });
    User.belongsToMany(models.user, { 
        through: 'users_followers', 
        foreignKey: 'follower_id',
        otherKey: 'following_id',
        as: 'followers', 
    });
    User.belongsToMany(models.user, { 
        through: 'users_followers', 
        foreignKey: 'following_id',
        otherKey: 'follower_id',
        as: 'following', 
    });

  return User;
};

module.exports = user;

关于创建多对多关联，我做错了什么吗？我问是因为我一直在尝试差异变化但是在尝试 include: [db.follower]

时无法执行查询

感谢大家的帮助

附加信息

查询运行是：

const fetchUser = async (root, args, context) => {
  const { db, user } = await context();
  const { id } = args;
  
  const fetchedUser = await db.user.findOne({ 
      attributes: {
          include: [
            [sequelize.literal('(select count(*) from users_followers where users_followers.follower_id=users.id)'), 'followers_count'],
        ]
    },
    include: [
        'followers',
        'following'
    ],
    where: { 
        id 
    }, 
    raw: true 
});

return fetchedUser;

Answer 1

在 include 选项中，您始终应指明位于已定义关联另一端的模型。在这种情况下，它是具有两个不同别名的 User 模型：

include: [
{
  model: db.user,
  as: 'followers'
}, {
  model: db.user,
  as: 'following'
}],

无法使用 belongsToMany 正确使用多对多

Unable to correctly use many-to-many using belongsToMany

sequelize.js