“分组依据"流星收集查询 [英] "group by" queries on meteor collection

问题描述

我的数据mongoDB:

>db.CUSTOMER.find()

{"Name": "A", "CreatedDate": "Wed Jan 29 2014"}

{"Name": "B", "CreatedDate": "Fri Jan 31 2014"}

{"Name": "C", "CreatedDate": "Sat Feb 01 2014"}

{"Name": "D", "CreatedDate": "Sat Feb 01 2014"}

在流星中:

Customer = new Meteor.Collection("CUSTOMER");

我正在尝试在流星收集中按日期(周一、周二、周三...)以及数据总数对它们进行分组.应该是这样的:

I'm trying to group them by date (Mon, Tues, Wed, ...) in meteor collection along with the total of the data. It should be something like this:

{"Date": "Wed Jan 29 2014", "Total" 1}

{"Date": "Fri Jan 31 2014", "Total" 1}

{"Date": "Sat Feb 01 2014", "Total" 2}

在 mongoDB 中，我会选择 http://docs.mongodb.org/manual/reference/method/db.collection.group/，但显然在meteor中是不可能的，因为它不支持findAndModify、upsert、聚合函数和map/reduce.

In mongoDB, I'd just go with http://docs.mongodb.org/manual/reference/method/db.collection.group/, but apparently, it is impossible in meteor, for it doesn't support findAndModify, upsert, aggregate functions, and map/reduce.

有没有我可以做的变通方法的例子来使它起作用?

Is there any examples of workaround that I can do to make it works?

谢谢

推荐答案

您需要手动将它们分组.有很多方法可以做到这一点，但这里有一个(诚然难以阅读)示例:

You'll need to group them manually. There are a number of ways to do that, but here's an (admittedly difficult to read) example:

var customers = Customer.find().fetch();

var groupedDates = _.groupBy(_.pluck(customers, 'CreatedDate'));

_.each(_.values(groupedDates), function(dates) {
  console.log({Date: dates[0], Total: dates.length});
});

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