javascript - node.js/express 路由中的 Mongoose 组查询

Question

您好，我有以下在 Robomongo 中执行的查询按预期工作:

db.av.group(
{
 key: { roomId: 1},
 cond: { dateOfDay: { $gte: new Date('12/01/2014'), $lt: new Date('12/30/2014') } },
 reduce: function( curr, result ) {
            result.total += curr.price;
            result.count++;
         },
 initial: { total : 0,
     count : 0
     },
     finalize: function(result) {
              result.avg = Math.round(result.total / result.count);
          }

  }
)

在 express 应用中实现后:

 app.get('/api/checkAv/:checkIn/:checkOut', function(req, res) {
        var checkIn = req.params.checkIn,
            checkOut = req.params.checkOut,
            roomType = req.params.roomType;

    model.Av.group(
    {
     key: { roomId: 1},
     cond: { dateOfDay: { $gte: new Date('12/01/2014'), $lt: new Date('12/30/2014') } },
     reduce: function( curr, result ) {
                result.total += curr.price;
                result.count++;
             },
     initial: { total : 0,
         count : 0
         },
         finalize: function(result) {
                  result.avg = Math.round(result.total / result.count);
              }

    }

    ).exec(function(err, av) {
        if (err)
            res.send(err);

        res.json(av);
    });
});

我进入控制台:

TypeError: Object function model(doc, fields, skipId) { if (!(this instanceof model)) return new model(doc, fields, skipId); Model.call(this, doc, fields, skipId); } has no method 'group' at /home/www/domain.com/api/routes/routes.js:58:18 at Layer.handle [as handle_request] (/home/www/domain.com/node_modules/express/lib/router/layer.js:82:5)
at next (/home/www/domain.com/node_modules/express/lib/router/route.js:100:13) at Route.dispatch (/home/www/domain.com/node_modules/express/lib/router/route.js:81:3)
at Layer.handle [as handle_request] (/home/www/domain.com/node_modules/express/lib/router/layer.js:82:5)
at /home/www/brasovapartments.com/node_modules/express/lib/router/index.js:234:24 at param (/home/www/domain.com/node_modules/express/lib/router/index.js:331:14) at param (/home/www/domain.com/node_modules/express/lib/router/index.js:347:14) at param (/home/www/domain.com/node_modules/express/lib/router/index.js:347:14) at Function.proto.process_params (/home/www/domain.com/node_modules/express/lib/router/index.js:391:3)

现在阅读周围我看到一些人定义了一个组属性，但不确定如何以及在 Mongoose 模式中的位置..？ 你能告诉我我的问题是什么吗？

Answer 1

group命令不受 Mongoose 支持，并且在 MongoDB 3.4 中也已弃用，因为使用 aggregate 可以更好地提供其功能。相反。

您可以通过 aggregate 使用类似的东西来做到这一点:

model.Av.aggregate([
    {$match: {dateOfDay: {$gte: new Date('12/01/2014'), $lt:new Date('12/30/2014')}}},
    {$group: {
        _id: '$roomId',
        total: {$sum: '$price'},
        count: {$sum: 1},
        avg: {$avg: '$price'}
    }}
], function (err, result) {...});

如果您不需要 total 和 count 字段，则可以省略它们，因为 $avg运算符可让您直接计算平均价格。