使用 sequelize 获取关联表的计数答案

【问题标题】：Get the count of Associated tables using sequelize使用 sequelize 获取关联表的计数
【发布时间】：2022-01-08 20:48:01
【问题描述】：

在我的案例中，帐户是一个父表帐户，它有许多成员，一个帐户有许多组，帐户有许多角色。因此，我尝试按如下方式对每个表进行计数。

  Account.findAll({
    subQuery: false, 

    where: {id: id},

    attributes: {
        include: ['*',
            [Sequelize.fn("COUNT", Sequelize.col("Members.id")), "usersCount"],
            [Sequelize.fn("COUNT", Sequelize.col("Groups.id")), "groupsCount"],
            [Sequelize.fn("COUNT", Sequelize.col("Roles.id")), "rolesCount"]]
    },
    include: [
        {
            model: Member, attributes: [], where: {accountId: id}
        },
        {
            model: Group, attributes: [], where: {accountId: id}
        },
        {
            model: Role, attributes: [], where: {accountId: id}
        }
    ],
    group: ['Account.id']
})
    .then(data => {
        let result = data.map(item => accountObj(item));
        return next(null, result[0]);
    })
    .catch(err => dbHelper.handleError(err, next));

它给了我一个错误的计数。还尝试了我在堆栈溢出时发现的各种其他选项。但没有找到上述查询的任何解决方案。

【问题讨论】：

标签： node.js postgresql sequelize.js

【解决方案1】：

您要么需要将此查询分成三个以分别计算每个子模型记录计数，要么删除include 和group 选项并将Sequelize.fn 替换为Sequelize.literal 子查询以计算子记录。

Account.findAll({
    where: {id: id},
    attributes: {
        include: ['*',
  [Sequelize.literal("(SELECT COUNT(*) from members as m where m.account_id=account.id)", "usersCount"],
  [Sequelize.literal("(SELECT COUNT(*) from groups as g where g.account_id=account.id)", "groupsCount"],
  [Sequelize.literal("(SELECT COUNT(*) from roles as r where r.account_id=account.id)", "rolesCount"],
  ]
    }
})

【讨论】：