Node used MongoDB

Brief introduction

MongoDB Chinese Documents

MongoDB is a product with function between relational databases and non-relational databases (nosql), non-relational database among the most feature-rich, like most relational databases.

Mongoose

Mongoose library can be used to connect to the database in the Node

mongoose Chinese Documents

npm i mongoose  -s

Basic Operation

Connect to the database

const mongoose = require('mongoose');

//连接指定数据库
mongoose.connect(
    'mongodb://ip地址/数据库名称',
    {
        useNewUrlParser: true,
        useUnifiedTopology: true
    }
);
const conn = mongoose.connection;
//绑定连接完成监听
conn.on('connected',function () {
    console.log('数据库连接成功');
})

Create a model

• Schema used to define the data structure of the object

• Model defined by mongoose.model (table name, data object)

//得到对应特定集合的model （文档：数据对象， 集合：数据表）
const Schema = mongoose.Schema;
const userSchema = new Schema({ //文档结构: 属性名\属性值
    name: { type: String, default: 'hahaha' },
    age: { type: Number, min: 18, index: true },
    bio: { type: String, match: /[a-z]/ },
    password: {type:String}
});

//定义Model
const UserModel = mongoose.model('user',userSchema);//创建了users集合

Additions and deletions to change search

Created by the Model step to implement the additions and deletions to change search

CRUD-related functions: https://mongoosejs.com/docs/queries.html

//增
function saveTest() {
    //创建实例
    const userModel = new UserModel({
        username: 'admin',
        age: 19,
        bio:"z",
        password:md5('12345') //利用 blueimp-md5库，将密码加密
    });

    userModel.save(function (err, data) {
        console.log('save()',err,data);
    })
}
//删
function deleteTest() {
    UserModel.deleteOne(
        {
            _id: '5e4d1c324abf031e98915a65'
        },(err, product) => {
         console.log('delete ',err,product);
        }
    )
}
//查 通过find()/findOne()/findById
function findTest() {
    UserModel.find(
        (err,doc)=>{
            console.log('find()',err,doc)
        }
    );

    UserModel.findOne({username: 'admin'},
        function (err,doc) {
            console.log('findOne()',err,doc)
        })
}

//改
function updateTest() {
    UserModel.findByIdAndUpdate({
        _id: '5e4d1c324abf031e98915a65'
    },{
        username: 'newName'
    },
        function (err,doc) {
            console.log('findByIdAndUpdate',err,doc)
        })
}

The official criteria query example

// With a JSON doc
Person.
  find({
    occupation: /host/,
    'name.last': 'Ghost',
    age: { $gt: 17, $lt: 66 },
    likes: { $in: ['vaporizing', 'talking'] }
  }).
  limit(10).
  sort({ occupation: -1 }).
  select({ name: 1, occupation: 1 }).
  exec(callback);

// Using query builder
Person.
  find({ occupation: /host/ }). //模糊查询：正则表达式
  where('name.last').equals('Ghost').
  where('age').gt(17).lt(66).
  where('likes').in(['vaporizing', 'talking']).
  limit(10).
  sort('-occupation').
  select('name occupation').
  exec(callback);

Conditional operator:
$ Within last Greater gt -------->

$gte --------- gt equal >=

$lt -------- less than <

$lte --------- lt equal <=

$ne ----------- not equal !=

$eq -------- equal =

$ In: [] satisfying one of the array in which the opposite is $ Nin

limit read skip a specified number of records to skip a specified number of records

Ascending lifting keyword: 'asc' / 'ascending' / 1 descending Keywords: 'desc' / 'Descending' / -1
// to "field" Ascending and "test" Descending
query.sort ({field: 'asc ', Test: -1});
// equivalent to
query.sort (' field -test ');

select for include and exclude certain attributes
// the include A and B, the exclude OTHER Fields
query.select ( 'A B');
// the exclude C and D, the include OTHER Fields
query.select ( '- C -d') ;