Introduction to Koa Session

Koa-session is a session middleware for Koa, a lightweight and expressive web framework for Node.js. It allows you to handle sessions with ease, providing a range of APIs to enhance your web application’s session management capabilities. In this article, we will delve into various APIs provided by koa-session and demonstrate their usage with code snippets.

Basic Setup

To get started with koa-session, you need to install it alongside koa:

npm install koa koa-session

Once installed, you can configure koa-session in your Koa app:

  const Koa = require('koa');
  const session = require('koa-session');
  const app = new Koa();

  app.keys = ['your-secret-key'];
  app.use(session(app));

  app.use(ctx => {
    if (!ctx.session.view) {
      ctx.session.view = 0;
    }
    ctx.session.view++;
    ctx.body = `${ctx.session.view} views`;
  });

  app.listen(3000);

Configuring koa-session

Koa-session provides a range of configuration options to customize its behavior:

  const CONFIG = {
    key: 'koa:sess', 
    maxAge: 86400000, 
    autoCommit: true, 
    overwrite: true, 
    httpOnly: true, 
    signed: true, 
    rolling: false, 
    renew: false, 
  };
  app.use(session(CONFIG, app));

API Examples

Here are some useful API examples to maximize the functionality of koa-session:

Setting Session

  app.use(ctx => {
    ctx.session.username = 'JohnDoe';
    ctx.body = 'Session Set!';
  });

Getting Session

  app.use(ctx => {
    const username = ctx.session.username;
    ctx.body = `Hello, ${username}`;
  });

Destroying Session

  app.use(ctx => {
    ctx.session = null;
    ctx.body = 'Session Destroyed';
  });

Session Rolling

If you want to renew the session ID on every request:

  const CONFIG = {
    rolling: true,
  };
  app.use(session(CONFIG, app));

Session Renew

If you want to renew session when it is about to expire:

  const CONFIG = {
    renew: true,
  };
  app.use(session(CONFIG, app));

Example App with Multiple APIs

  const Koa = require('koa');
  const session = require('koa-session');
  const app = new Koa();

  app.keys = ['your-secret-key'];

  const CONFIG = {
    key: 'koa:sess', 
    maxAge: 86400000, 
    autoCommit: true, 
    overwrite: true, 
    httpOnly: true, 
    signed: true, 
    rolling: true, 
    renew: false, 
  };

  app.use(session(CONFIG, app));

  app.use(ctx => {
    if (ctx.path === '/set') {
      ctx.session.user = 'JohnDoe';
      ctx.body = 'Session is set!';
    } else if (ctx.path === '/get') {
      ctx.body = `User: ${ctx.session.user}`;
    } else if (ctx.path === '/destroy') {
      ctx.session = null;
      ctx.body = 'Session destroyed!';
    } else {
      ctx.body = 'Hello World';
    }
  });

  app.listen(3000);

With these APIs, you can handle all your session management needs in a Koa application efficiently and securely.

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