mongoose.js：如何在使用填充时从引用的子数组中删除属性，并将子数组字段之一用作过滤器？

Question

我在使用猫鼬包的节点js中有以下代码。

1）如果我使用populate方法，如何在响应的Foundations数组中删除字段总数？ 导致该数组由对另一个集合的引用形成。

2）如何使用“ campaigns.state”字段仅过滤以“ ACTIVE”为状态的广告系列？

定义：

基金会模型

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

var foundation = new Schema({

     twitter_account:{type: String, required: true, unique: true},

     name:{type: String, required: true, unique: true},

     pic_path: {type: String, required: true},

     doc_path: {type: String, required: true},

     campaigns: [{type: Schema.ObjectId, ref: 'Campaign'}]
},{
    timestamps: true
});

module.exports = mongoose.model('Foundation', foundation);

在Campaigns模型上，我有Foundations字段，该字段是对Foundations的引用数组，我想在响应中将其切出以避免冗余

var campaign = new Schema({

.............

     foundations: [{type: Schema.ObjectId, ref: 'Foundation'}],

......................
}

在这里检索数据的API路线

var express = require('express');
var router = express.Router();
var Foundation=require('../models/Foundation');
var mongoose= require('mongoose');
var Promise = require("bluebird");
var _ = require('lodash');


//get all Foundations
router.get('/get/all', function(req, res, next) {

  var results=Foundation.find({},{twitter_account:1,name:1,campaigns:1})

  .populate('campaigns').exec(function (err, foundation) {
        if (err) return handleError(err);
        console.log(foundation);
        res.send(foundation);
});

});

module.exports = router;

这是响应：

[
  {
    "_id": "58229b253e1ad628e1ed975e",
    "twitter_account": "@YYYYYYYYYYYY",
    "name": "YYYYYYYYYYYY",
    "campaigns": [
      {
        "_id": "5822a9444aea133044b6eb84",
        "updatedAt": "2016-11-09T04:42:44.922Z",
        "createdAt": "2016-11-09T04:42:44.922Z",
         "total": 0,
        "state": "ACTIVE",
        "__v": 0,
        "end_date": null,
        "foundations": [
          "58229b253e1ad628e1ed975e",
          "58229b253e1ad628e1ed975f"
        ]
      },
      {
        "_id": "5822a9444aea133044b6eb85",
        "updatedAt": "2016-11-09T04:42:44.925Z",
        "createdAt": "2016-11-09T04:42:44.925Z",
        "remaining_ammount_to_goal": 500000,
        "total": 0,
        "state": "ACTIVE",
        "__v": 0,
        "end_date": null,
        "foundations": [
          "58229b253e1ad628e1ed975e"
        ]
      }
    ]
  },
  {
    "_id": "58229b253e1ad628e1ed975f",
    "twitter_account": "@XXXXXXXXXXX",
    "name": "XXXXXXXXX",
    "campaigns": [
      {
        "_id": "5822a9444aea133044b6eb85",
        "updatedAt": "2016-11-09T04:42:44.925Z",
        "createdAt": "2016-11-09T04:42:44.925Z",
        "total": 0,
        "state": "ACTIVE",
        "__v": 0,
        "end_date": null,
        "foundations": [
          "58229b253e1ad628e1ed975e"
        ]
      }
    ]

所需的响应（只想在Campaigns对象中放置基础数组字段）：

[
  {
    "_id": "58229b253e1ad628e1ed975e",
    "twitter_account": "@YYYYYYYYYYYY",
    "name": "YYYYYYYYYYYY",
    "campaigns": [
      {
        "_id": "5822a9444aea133044b6eb84",
        "updatedAt": "2016-11-09T04:42:44.922Z",
        "createdAt": "2016-11-09T04:42:44.922Z",
         "total": 0,
        "state": "ACTIVE",
        "__v": 0,
        "end_date": null
      },
      {
        "_id": "5822a9444aea133044b6eb85",
        "updatedAt": "2016-11-09T04:42:44.925Z",
        "createdAt": "2016-11-09T04:42:44.925Z",
        "remaining_ammount_to_goal": 500000,
        "total": 0,
        "state": "ACTIVE",
        "__v": 0,
        "end_date": null
      }
    ]
  },
  {
    "_id": "58229b253e1ad628e1ed975f",
    "twitter_account": "@XXXXXXXXXXX",
    "name": "XXXXXXXXX",
    "campaigns": [
      {
        "_id": "5822a9444aea133044b6eb85",
        "updatedAt": "2016-11-09T04:42:44.925Z",
        "createdAt": "2016-11-09T04:42:44.925Z",
        "total": 0,
        "state": "ACTIVE",
        "__v": 0,
        "end_date": null
      }
    ]

有任何想法吗？。 非常感谢你！！！

编辑 ：供以后参考，使用填充过滤器在“ Campaigns” JSONArray上具有state =“ Active”的对象，我使用以下方法实现了此目的：var results = Foundation.find（{}，{twitter_account：1，name：1，campaigns ：1}）

  .populate({path : 'campaigns' ,select :'-foundations', match:{state:'ACTIVE'}}).exec(function (err, foundation) {
        if (err) return handleError(err);
        console.log(foundation);
        res.send(foundation);
});

Answer 1

您可以使用select填充

       var results=Foundation.find({},{twitter_account:1,name:1,campaigns:1})
          .populate({path : 'campaigns' ,select :'-foundations'})
          .exec(function (err, foundation) {
                if (err) return handleError(err);
                console.log(foundation);
                res.send(foundation);
        });

只需浏览猫鼬文档http://mongoosejs.com/docs/populate.html