如何在猫鼬中使用Aggregate

Question

如何在mongoose中定义以下MongoDB聚合查询:

db.contacts.aggregate([{$group: { "_id": { code: "$Code", name: "$Name" } } }])

查询的目的是提取不同代码和名称的列表.

我目前的型号代码是:

'use strict';

var mongoose = require('mongoose'),
    Schema = mongoose.Schema,
    ObjectId = Schema.ObjectId;

var fields = {
    Code: { type: String },
    Name: { type: String }
};

var contactSchema = new Schema(fields);

module.exports = mongoose.model('Contacts', contactSchema);

路由器看起来像这样:

api.contacts = function (req, res) {
Contacts.find({ AgencyTranslation: /^BROADCASTING/ }, function(err, contacts) {
  if (err) {
    res.json(500, err);
  } else {    
    res.json({contacts: contacts});
  }
});

我尝试了各种变体,还查看了示例代码:mongoose API docs,但我似乎无法让它工作.

(注意:以上查询在MongoDB控制台中有效.)

Answer 1

试试这个

Contacts.aggregate({$group: { "_id": { code: "$Code", name: "$Name" } } }, function(err, contacts) {
   ...
});

或者,$match如果你需要这个AgencyTranslation: /^BROADCASTING/条件

Contacts.aggregate([
  { $match : { AgencyTranslation: /^BROADCASTING/ } },
  { $group: { "_id": { code: "$Code", name: "$Name" } } }
], function(err, contacts) {
  // ...
});