nodejs gets request session

Node.js is a server-side JavaScript runtime environment that is fast, cross-platform, modular and can build efficient and stable server-side applications. When developing web applications, SESSION will be used, so how to get the request SESSION information in Node.js? This article will introduce how to obtain the request SESSION from the aspects of the concept of SESSION, the corresponding modules of Session in Node.js and specific API information.

1. The concept of SESSION

SESSION is a cross-request mechanism used to store user information and operations. By saving the SESSION variable, users can stay logged in when visiting different pages of the website. state and pass data between different pages. SESSION is a server-side state retention method, which assigns a unique ID to each session, and then saves the ID on the client (usually in the client's cookie) to achieve communication and communication between the server and the client. track. For each new session, a new ID is created for tracking.

In web development, SESSION can be used to optimize security, improve user experience, realize user specific needs, etc.

2. The use of Session in Node.js

In Node.js, there is a commonly used SESSION module express-session, which can add session support to Express applications. We might as well learn how to use it:

1. Install the express-session module

Enter the following command on the command line:

npm install express-session

2. Introduce express- into the project session:

In your project, add the following code:

var express = require('express');
var session = require('express-session');
var app = express();

3. Use express-session middleware

In your project, add the following code:

app.use(session({
secret: 'keyboard cat',//secret的值建议使用随机字符串
cookie: { maxAge: 60000 },
resave: true,
saveUninitialized: true
}))

Among them:

• secret is the key used for Session ID encryption, which can be set at will
• The maxAge in the cookie is the validity period that defines the Session ID
• resave:true means that the session is re-stored for each request, regardless of whether it changes.
• saveUninitialized:true means the user is not logged in, and the Session and Cookie will be reset for each request

4. Set and obtain SESSION

in your project , you can set and obtain SESSION through the following code:

Setting:

req.session.userName="tom";

Getting:

var userName = req.session.userName;

Next, we will use examples to explain how Get request SESSION information in Node.js.

3. Specific API information

In order to better understand how to obtain the requested SESSION information, let’s first understand the API corresponding to SESSION in Node.js.

req.session

This is the request middleware of session, which can realize dialogue control by writing req.session. Usage example is:

req.session.userName='xiaoming';

The above code implements adding userName to the session. In Express, conversation information is stored in a session, which is an object that can be manipulated like a normal JavaScript object.

req.session.destroy

This attribute indicates that when the user exits, the data saved in the session will be cleared. Usage examples are:

req.session.destroy(function(err) {
  // cannot access session here
})

When the session is destroyed, the callback function will be executed.

4. Example Demonstration

Next, we use an example to demonstrate how to obtain the request SESSION information.

1. Create the project

First, initialize the project and create the main.js file:

mkdir node-app && cd node-app
npm init
touch main.js

2. Install express and express-session and introduce

Enter the following command in the command line to install express and express-session and import:

npm install express --save
npm install express-session --save

Write the following code in main.js:

const express = require('express')
const session = require('express-session')

const app = express()

app.use(session({
  secret: 'keyboard cat',//secret的值建议使用随机字符串
  cookie: { maxAge: 60000 },
  resave: true,
  saveUninitialized: true
}))

app.get('/login', (req, res) => {
  req.session.userName = 'Qiming'
  res.send('login success')
})

app.get('/home', (req, res) => {
  let userName = req.session.userName
  if (userName) {
    res.send(`welcome ${userName}`)
  } else {
    res.send('please login first')
  }
})

const server = app.listen(3000, () => {
  console.log(`app is running at http://localhost:${server.address().port}`)
})

In the above code:

• First introduce the express and express-session modules
• Create the application app object and add the session middleware in the middle
• When accessing/login, store the user name in req.session .userName
• When accessing /home, try to get the userName from req.session. If it exists, welcome and give a message, otherwise prompt the user to log in first
• Listen at 3000 when the application starts On the port, output the startup log information

3. Run the project and test

Run the following command in the terminal:

node main.js

Open the browser and visit http: //localhost:3000/login, get the "login success" message, visit http://localhost:3000/home, get the "welcome Qiming" message, indicating that the SESSION is obtained successfully.

5. Summary

In this article, we have learned about the concept of SESSION, the use of SESSION in Node.js, specific API information and a demonstration example, hoping to help everyone better understand Learn how to get request SESSION information in Node.js. In actual projects, how to use SESSION needs to be decided according to the actual situation, and can be implemented according to business needs.

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