1. Software configuration:
1.node v8.9.3
2. npm 5.5.1
3. For the mongoose and MongoDB versions, see package.json below.
// package.json
{
"name": "mongoosedemo",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "",
"license": "ISC",
"dependencies": {
"mongodb": "^3.1.1",
"mongoose": "^5.2.4"
}
}
2. Connection string
2.1 Connection String
// db.js
const mongoose = require('mongoose');
const DB_URL = 'mongodb://localhost:27017/mydatabase1';
// Connect
mongoose.connect(DB_URL, { useNewUrlParser: true });
// Successful connection
mongoose.connection.on('connected', function () {
console.log('Mongoose connection open to ' + DB_URL);
})
// Connection exception
mongoose.connection.on('error', function (err) {
console.log('Mongoose connection error ' + err);
})
// Connection disconnect
mongoose.connection.on('disconnected', function () {
console.log('Mongoose connection disconnected ');
})
// Modify the last line of db.js above to export the mongoose object
const mongoose = require('mongoose');
const DB_URL = 'mongodb://localhost:27017/mydatabase1';
// Connect
mongoose.connect(DB_URL, { useNewUrlParser: true });
// Successful connection
mongoose.connection.on('connected', function () {
console.log('Mongoose connection open to ' + DB_URL);
})
// Connection exception
mongoose.connection.on('error', function (err) {
console.log('Mongoose connection error ' + err);
})
// Connection disconnect
mongoose.connection.on('disconnected', function () {
console.log('Mongoose connection disconnected ');
})
module.exports = mongoose;
2.2 Schema
// Define a user's Schema, named user.js
/**
* User information
*/
// Define database table storage structure
const mongoose = require('./db');
const Schema = mongoose.Schema;
const UserSchema = new Schema({
username: { type: String }, // User name
password: { type: String }, // User password
age: { type: String }, // User age
lastLoinDate: { type: Date } // Last logon time
})
2.3 Model
With Schema defined, the next step is to generate the Model.
Model is a schema-generated model that can operate on databases
// Modify the user.js above, convert Schema to Model, and export
// user.js
/**
* User information
*/
// Define database table storage structure
const mongoose = require('./db');
const Schema = mongoose.Schema;
const UserSchema = new Schema({
username: { type: String }, // User name
password: { type: String }, // User password
age: { type: String }, // User age
lastLoinDate: { type: Date } // Last logon time
})
// Generate Model
module.exports = mongoose.model('User', UserSchema);CRUD operation
3.1 insertion
Model#save([fn])
New test.js
const User = require('./user');
// insert
function insert() {
var user = new User({
username: "Chen Er dog", // User name
password: "abc123", // User password
age: 18, // User age
lastLoinDate: new Date() // Last logon time
});
user.save(function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
insert();
node test.js
3.2 update
Model.update(conditions, update, [options], [callback])
// test1.js
const User = require('./user');
// To update
function update() {
var whereStr = {"username": "Chen Er dog"};
var updateStr = {"password": "123456"};
User.update(whereStr, updateStr, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
update();
node test1.js 
The common method is findByIdAndUpdate, which is specified according to _id.
Model.findByIdAndUpdate(id, [update], [options], [callback])
// test12.js
const User = require('./user');
// Update according to ID
function findByIdAndUpdate() {
var id = "5b5333a114cf2d337c6bd971";
var updateStr = {"password": "aabbcc"};
User.findByIdAndUpdate(id, updateStr, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
findByIdAndUpdate();
Other update methods
Model.findOne AndUpdate ([conditions], [update], [options], [callback]) // Find a record and update it
3.3 delete
Model.remove(conditions, [callback])
// test2.js
const User = require('./user');
// delete
function del() {
var whereStr = {"username": "Chen Er dog"};
User.remove(whereStr, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
del();
Other commonly used methods are:
Model.findByIdAndRemove(id, [options], [callback])
Model.findOneAndRemove(conditions, [options], [callback])
3.4 Conditional Query
Some test data have been inserted first. 
Model.find(conditions, [fields], [options], [callback])
const User = require('./user');
// Conditional query
function getByConditions() {
var whereStr = {"username": "Chen Er dog 1"};
User.find(whereStr, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
getByConditions();
The second parameter can set the fields to query the output, such as changing to
const User = require('./user');
// Conditional query (set the second parameter)
function getByConditions() {
var whereStr = {"username": "Chen Er dog 1"};
var opt = {"username": 1, "_id": 0};
User.find(whereStr, opt, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
getByConditions();
The output will only have a username field, which is set as follows: 1 for query output, 0 for no output
3.4.1 Query Age
const User = require('./user');
// Conditional query
function getByConditions() {
// var whereStr = {"username": "Chen Erguo 1"};
// var opt = {"username": 1, "_id": 0};
// User.find(whereStr, opt, function (err, docs) {
// Query age is greater than 20 and less than or equal to 50
User.find({"age": {$gte: 20, $lte: 50 }}, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
getByConditions();
3.4.2
or relationship Or negativity $gt > More than or equal to $gte Less than $lt Less than or equal to $ne is not equal to In is in a range of values $nin is not in the range of multiple values Multiple values in the $all matching array $regex regular for fuzzy queries Matching array size maxDistance range query, distance (based on LBS) mod near. Neighborhood query, query the location nearby (based on LBS) Does the $exists field exist? $elemMatch Matches the elements in the inner array within range query (based on LBS) Range query, rectangular range (based on LBS) center range alert, circular range (based on LBS) Center Sphere Range Query, Spherical Range (LBS-based) Slce: Query for elements in the field set (e.g. from the number after, N to M first elements)
3.5 Quantity Query
Model.count(conditions, [callback])
const User = require('./user');
// Quantity query
function getCountByConditions() {
var whereStr = {};
// User.count(whereStr, function (err, docs) {
User.countDocuments(whereStr, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
getCountByConditions();
After amendment: 
3.6 Query by _id
Model.findById(id, [fields], [options], [callback])
const User = require('./user');
// Query by _id
function getById () {
var id = "5b536b314cfb3f0d54a53d37"
User.findById(id, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
getById ();
3.7 Fuzzy Query
Additional data 
const User = require('./user');
// Fuzzy query
// Find out that all user names have'm'names and are case-insensitive
function getByRegex () {
var whereStr = {"username": {$regex: /m/i}};
User.find(whereStr, function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
getByRegex ();
3.8 Paging Query
const User = require('./user');
// Paging query
function getByPager () {
var pageSize = 5; // How many items per page?
var currentPage = 1; // What is the current page?
var sort = {'lastLoinDate': -1}; // Reverse by login time
var condition = {};
var skipnum = (currentPage - 1) * pageSize; // Skipping number
User.find(condition).skip(skipnum).limit(pageSize).sort(sort).exec(function (err, docs) {
if(err) {
console.log("Error: " + err);
} else {
console.log("docs: " + docs);
}
})
}
getByPager ();
CurrtPage = 1 
CurrtPage = 2 
3.9 Other Common Methods
Model.distinct(field, [conditions], [callback]) //Duplicate removal
Model.findOne(conditions, [fields], [options], [callback]) //Find a record
Model.findOneAndRemove(conditions, [options], [callback]) //Find a record and delete it
Model.findOneAndUpdate([conditions], [update], [options], [callback]) //Find a record and update itmongodb Learning (3) - NodeJs Manipulates mongodb with mongoose
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