sequelize.js - 将子查询序列化为字段

Question

我正在尝试通过 sequelized 生成这样的查询:

SELECT 
    "Customers"."id", 
    (SELECT SUM("Orders"."amount") FROM "Orders"
     WHERE "Orders"."CustomerId" = "Customers"."id") AS "totalAmount",
    "Customer"."lastName" AS "Customer.lastName",
    "Customer"."firstName" AS "Customer.firstName" 
FROM "Customers" AS "Customer";

我试图避免 GROUP BY子句，因为我有很多字段要选择，而且我不想将它们全部分组(我认为它效率不高，不是吗？)

我已经尝试了几种通过 sequelize 实现它的方法，包括 {include: ...}和 {attributes: [[...]]} ，但没有任何运气。

有任何想法吗？或者我应该用一个大的 GROUP BY子句并让所有“常规”字段分组？

Answer 1

您最好的选择是:

    return Customer.findAll({
        attributes: Object.keys(Customer.attributes).concat([
            [sequelize.literal('(SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id")'), 'totalAmount']
        ])
    });

这看起来像是问题 #1869 的扩展:

Querying on the through model/join table is not possible currently unfortuneatly.

您的问题也与 this one 相关。 ，那里的问题有点像“为每个用户查询关联表”。

看着 test code为 include条款我没有看到任何组选项，这是此功能缺乏证据。

解决方案:

当然，您可以只传递查询“raw”:

    return sequelize.query(
        'SELECT *, (SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id") AS "totalAmount" FROM "Customers" AS "Customer";',
        Customer,
        {raw: false}
    );

这会给你想要的，并包装成 Customer实例。

或者，您可以添加一个返回另一个 promise 的实例方法:

instanceMethods: {
    getOrderSummary: function () {
        return Order.findAll({
            where: {
                CustomerId: this.id
            },
            attributes: [
                [sequelize.fn('SUM', sequelize.col('amount')), 'sum'],
                'CustomerId'],
            group: ['CustomerId']
        });
    }
}

实例方法版本不是很干净，但它可以正常工作，并且根据您的情况可能更合适。

我发现的最佳解决方案是在 attribute 中使用 SQL 文字。查询的字段。唯一的缺点是它似乎在选择其他属性时把石板擦干净了，而 '*' 不会削减它。因此，您需要使用 Object.keys() 来解决此问题。 .

    return Customer.findAll({
        attributes: Object.keys(Customer.attributes).concat([
            [sequelize.literal('(SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id")'), 'totalAmount']
        ])
    });

尽管如此，它还是很有魅力，您可以将它用于一些更有趣的嵌套 SELECT。还有那个 findAll给了我们正确的:

Executing (default): SELECT "id", "firstName", "lastName", "createdAt", "updatedAt", (SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id") AS "totalAmount" FROM "Customers" AS "Customer";
{ id: 1,
  firstName: 'Test',
  lastName: 'Testerson',
  createdAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  updatedAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  totalAmount: 15 }
{ id: 2,
  firstName: 'Invisible',
  lastName: 'Hand',
  createdAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  updatedAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  totalAmount: 99 }

顺便说一句，我也尝试向后做，并在 Order 上使用 GROUP BY型号选择进入 Customer模型，但这不起作用:

    // Doesn't work
    return Order.findAll({
        attributes: [
            [Sequelize.fn('COUNT', '*'), 'orderCount'],
            'CustomerId'
        ],
        include: [
            {model: Customer, attributes: ['id']}
        ],
        group: ['CustomerId']
    });