Introduction to koa-session

Koa-session is a powerful session management middleware for Koa.js, allowing developers to easily manage user sessions in their Koa applications. This middleware offers a wide array of functionalities that can significantly ease the handling of session data.

Below is an in-depth look at various APIs provided by koa-session, accompanied by practical code snippets.

Getting Started

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

    const app = new Koa();
    app.keys = ['some secret hurr'];

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

    app.use(session(CONFIG, app));
    app.use(ctx => {
      if (ctx.path === '/favicon.ico') return;
      let n = ctx.session.views || 0;
      ctx.session.views = ++n;
      ctx.body = `This is visit number ${n}`;
    });

    app.listen(3000);
  

API Examples

Setting Session Data

  
    app.use(ctx => {
      ctx.session.user = {
        name: 'John Doe',
        role: 'admin',
      };
      ctx.body = 'User session data has been set';
    });
  

Fetching Session Data

  
    app.use(ctx => {
      const user = ctx.session.user;
      ctx.body = `User name is ${user.name} and role is ${user.role}`;
    });
  

Destroying Session

  
    app.use(ctx => {
      if (ctx.path === '/logout') {
        ctx.session = null;
        ctx.body = 'Session destroyed';
      }
    });
  

Custom Session Key

  
    const CONFIG = {
      key: 'my.custom.session.key',
      /** other configuration options */
    };
    app.use(session(CONFIG, app));
  

Setting Expiration Time

  
    const CONFIG = {
      maxAge: 60000, // 1 minute
    };
    app.use(session(CONFIG, app));
  

Rolling Sessions

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

Full Application Example

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

    const app = new Koa();
    app.keys = ['super-secret-key'];

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

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

    app.use(ctx => {
      if (ctx.path === '/set') {
        ctx.session.user = { name: 'Alice' };
        ctx.body = 'User session data set.';
      } else if (ctx.path === '/get') {
        const user = ctx.session.user;
        ctx.body = user ? `User name: ${user.name}` : 'No session data found';
      } else if (ctx.path === '/destroy') {
        ctx.session = null;
        ctx.body = 'Session destroyed.';
      } else {
        ctx.body = 'Hello, Koa.js with Sessions!';
      }
    });

    app.listen(3000, () => {
      console.log('Server running on http://localhost:3000');
    });
  

Conclusion

Koa-session simplifies the process of managing user sessions in Koa.js applications. By leveraging the myriad of options provided by this middleware, developers can create robust session management mechanisms catering to various requirements.

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