Mongoose 多表（N個表）關聯查詢aggregate

Mongoose 多表（N個表）關聯查詢概述

需求：文章（article），文章分類（articlecate），用戶（user）這三個表之間的關系，一篇文章對應文章分類表中的某個類型，對應着用戶表中的某個用戶

 

 

 

Mongoose 多表（N個表）關聯查詢代碼實現

首先我們需要創建db.js（連接數據庫）的模塊

var mongoose = require('mongoose');

mongoose.connect('mongodb://127.0.0.1:27017/eggcms',{ useNewUrlParser: true },function(err){
  if(err){
    console.log(err);
    return;
  }
  console.log('數據庫連接成功')
});

module.exports = mongoose;

通過上面的需求我們需要建立三個model模塊分別是article.js，articlecate.js，user.js

var mongoose = require('./db.js');
var Schema = mongoose.Schema;

var ArticleSchema = new Schema({
    title: {
        type: String,
        unique: true
    },
    cid: { // 分類id
        type: Schema.Types.ObjectId
    },

    author_id:{ // 用戶的id
        type: Schema.Types.ObjectId
    },
    author_name:{
        type:String
    },
    descripton: String,
    content: String
});


module.exports = mongoose.model('Article',ArticleSchema,'article');

var mongoose = require('./db.js');

var ArticleCateSchema = new mongoose.Schema({
    title  : {
        type: String,
        unique: true
    },
    descripton: String,
    addtime: {
        type: Date
    }
});


module.exports = mongoose.model('ArticleCate',ArticleCateSchema,'articlecate');

var mongoose = require('./db.js');

var UserSchema = new mongoose.Schema({
    username: { 
        type: String, 
        unique: true 
    },
    password: String,
    name: String,
    age: Number,
    sex: String,
    tel: Number,
    status: {
        type: Number,
        default: 1
    }
});

module.exports = mongoose.model('User',UserSchema,'user');

然后分別對應三個添加數據的模塊article_add.js，articlecate_add.js，user_add.js

var ArticleModel = require('./model/article.js');

var article = new ArticleModel();
article.title="這是一個國際新聞333333333"
article.cid='5cde87e21ebf22597c973f1f';   // 分類id
article.author_id='5cde88f71faa8045e439838b'; // 用戶id
article.author_name='李四';
article.descripton='這是一個國際新聞333333333333 此處省略300字';
article.content='訪問美國 這是一個國際新聞333333333'


article.save();

var ArticleCateModel = require('./model/articlecate.js');


// 分類的增加
var cate = new ArticleCateModel({
  title:'地方新聞',
  description:'地方新聞'
})

cate.save();

var UserModel = require('./model/user.js');

// 增加用戶
var user= new UserModel({
  username  :'wangwu',
  password:'qwerqwerqewrq',
  name:'王五',
  age:21,
  sex:'男',
  tel:[phone]
})
user.save();

當我們添加了一些數據之后再app.js中進行數據庫查詢的操作

查詢文章信息

var ArticleModel = require('./model/article.js')

// 查詢文章信息
ArticleModel.find({}, (err,docs) => {
  console.log(docs)
})

兩個表關聯查詢

var ArticleModel = require('./model/article.js');


//兩個表關聯查詢
ArticleModel.aggregate([
  {
    $lookup: {
      from: "articlecate",
      localField: "cid",
      foreignField: "_id",
      as: "cate"
    }
  }

],function(err,docs){
  console.log(JSON.stringify(docs))
})

將其轉成正常的JSON便於查看效果

多表關聯查詢

查詢文章信息 並顯示文章的分類 以及文章的作者信息

var ArticleModel = require('./model/article.js');

// 查詢文章信息 並顯示文章的分類 以及文章的作者信息
// 三個表關聯查詢
ArticleModel.aggregate([
{
  $lookup: {
    from: "articlecate",
    localField: "cid",
    foreignField: "_id",
    as: "cate"
  }
},
{
  $lookup: {
    from: "user",
    localField: "author_id",
    foreignField: "_id",
    as: "user"
  }
}

],function(err,docs){
  console.log(JSON.stringify(docs));
})

將其轉成正常的JSON便於查看效果

[{
    "_id": "5cde89b2ecdd5e4864bdaa44",
    "title": "這是一個國內新聞11111111",
    "cid": "5cde87ce5ac6d7551041c568",
    "author_id": "5cde8913a0e31553449bdf54",
    "author_name": "王五",
    "descripton": "這是一個國內新聞11111111 此處省略300字",
    "content": "訪問美國 這是一個國內新聞11111111",
    "__v": 0,
    "cate": [{
        "_id": "5cde87ce5ac6d7551041c568",
        "title": "國內新聞",
        "__v": 0
    }],
    "user": [{
        "_id": "5cde8913a0e31553449bdf54",
        "status": 1,
        "username": "wangwu",
        "password": "qwerqwerqewrq",
        "name": "王五",
        "age": 21,
        "sex": "男",
        "tel": 12345678987,
        "__v": 0
    }]
}, {
    "_id": "5cde89dc0d116f45fca7f559",
    "title": "這是一個國際新聞222222222222",
    "cid": "5cde87e21ebf22597c973f1f",
    "author_id": "5cde8913a0e31553449bdf54",
    "author_name": "王五",
    "descripton": "這是一個國際新聞222222222222 此處省略300字",
    "content": "訪問美國 這是一個國際新聞222222222222",
    "__v": 0,
    "cate": [{
        "_id": "5cde87e21ebf22597c973f1f",
        "title": "國際新聞",
        "__v": 0
    }],
    "user": [{
        "_id": "5cde8913a0e31553449bdf54",
        "status": 1,
        "username": "wangwu",
        "password": "qwerqwerqewrq",
        "name": "王五",
        "age": 21,
        "sex": "男",
        "tel": 12345678987,
        "__v": 0
    }]
}, {
    "_id": "5cde8a078a1ab250f4dbb8e0",
    "title": "這是一個國際新聞333333333",
    "cid": "5cde87e21ebf22597c973f1f",
    "author_id": "5cde88f71faa8045e439838b",
    "author_name": "李四",
    "descripton": "這是一個國際新聞333333333333 此處省略300字",
    "content": "訪問美國 這是一個國際新聞333333333",
    "__v": 0,
    "cate": [{
        "_id": "5cde87e21ebf22597c973f1f",
        "title": "國際新聞",
        "__v": 0
    }],
    "user": [{
        "_id": "5cde88f71faa8045e439838b",
        "status": 1,
        "username": "lisi",
        "password": "13214lkisisgfdsgsdsg",
        "name": "李四",
        "age": 20,
        "sex": "男",
        "tel": 124212142151,
        "__v": 0
    }]
}]