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koa-session

koa-session

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Simple session middleware for Koa. default is cookie-based session and support external store.

Requires Node 7.6 or greater for async/await support

Installation

$ npm install koa-session

Example

View counter example:

const session = require('koa-session');
const Koa = require('koa');
const app = new Koa();
 
app.keys = ['some secret hurr'];
 
const CONFIG = {
  key: 'koa:sess', /** (string) cookie key (default is koa:sess) */
  /** (number || 'session') maxAge in ms (default is 1 days) */
  /** 'session' will result in a cookie that expires when session/browser is closed */
  /** Warning: If a session cookie is stolen, this cookie will never expire */
  maxAge: 86400000,
  overwrite: true, /** (boolean) can overwrite or not (default true) */
  httpOnly: true, /** (boolean) httpOnly or not (default true) */
  signed: true, /** (boolean) signed or not (default true) */
  rolling: false, /** (boolean) Force a session identifier cookie to be set on every response. The expiration is reset to the original maxAge, resetting the expiration countdown. default is false **/
};
 
app.use(session(CONFIG, app));
// or if you prefer all default config, just use => app.use(session(app)); 
 
app.use(ctx => {
  // ignore favicon 
  if (ctx.path === '/favicon.ico') return;
 
  let n = ctx.session.views || 0;
  ctx.session.views = ++n;
  ctx.body = n + ' views';
});
 
app.listen(3000);
console.log('listening on port 3000');

API

Options

The cookie name is controlled by the key option, which defaults to "koa:sess". All other options are passed to ctx.cookies.get() and ctx.cookies.set() allowing you to control security, domain, path, and signing among other settings.

Custom encode/decode Support

Use options.encode and options.decode to customize your own encode/decode methods.

Hooks

  • valid(): valid session value before use it
  • beforeSave(): hook before save session

External Session Stores

Session will store in cookie by default, but it has some disadvantages:

You can store the session content in external stores(redis, mongodb or other DBs) by pass options.store with three methods(need to be async function):

  • get(key, maxAge, { rolling }): get session object by key
  • set(key, sess, maxAge, { rolling, changed }): set session object for key, with a maxAge (in ms)
  • destroy(key): destroy session for key

Once you passed options.store, session is strong dependent on your external store, you can't access session if your external store is down. Use external session stores only if necessary, avoid use session as a cache, keep session lean and stored by cookie!

The way of generating external session id is controlled by the options.genid, which defaults to uid.sync(24).

If you want to add prefix for all external session id, you can use options.prefix, it will not work if options.genid present.

If your session store requires data or utilities from context, opts.ContextStore is alse supported. ContextStore must be a class which claims three instance methods demonstrated above. new ContextStore(ctx) will be executed on every request.

Session#isNew

Returns true if the session is new.

if (this.session.isNew) {
  // user has not logged in 
} else {
  // user has already logged in 
}

Session#maxAge

Get cookie's maxAge.

Session#maxAge=

Set cookie's maxAge.

Session#save()

Save this session no matter whether it is populated.

Destroying a session

To destroy a session simply set it to null:

this.session = null;

License

MIT