How can I implement authentication in a Koa router?

How can I implement authentication in a Koa router?

You can implement authentication in a Koa router by using middleware to check for valid tokens or session data.

What libraries should I use for token-based authentication?

You can use libraries like jsonwebtoken for creating tokens and koa-jwt for middleware to protect your routes.

Can you show me a code example?

Sure! Here's a simple example:

const Koa = require('koa');
const Router = require('koa-router');
const jwt = require('jsonwebtoken');

const app = new Koa();
const router = new Router();

const secret = 'your_secret_key';

router.post('/login', async (ctx) => {
    const user = { id: 1, username: 'user' }; // Example user
    const token = jwt.sign(user, secret);
    ctx.body = { token };
});

const auth = async (ctx, next) => {
    const token = ctx.headers['authorization'];
    if (token) {
        try {
            ctx.state.user = jwt.verify(token, secret);
            await next();
        } catch (err) {
            ctx.status = 401;
            ctx.body = 'Unauthorized';
        }
    } else {
        ctx.status = 401;
        ctx.body = 'Unauthorized';
    }
};

router.get('/protected', auth, (ctx) => {
    ctx.body = 'This is a protected route!';
});

app.use(router.routes()).use(router.allowedMethods());
app.listen(3000);

This sets up a basic authentication flow.

What if I want to use session-based authentication instead?

For session-based authentication, you can use koa-session to manage user sessions. You would store user data in the session after login.