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https://github.com/lzztt/koa-session-minimal

Minimal implementation of session middleware for Koa 2
https://github.com/lzztt/koa-session-minimal

koa-middleware koa2 session-middleware

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Minimal implementation of session middleware for Koa 2

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# koa-session-minimal



[![NPM version][npm-image]][npm-url]

[![Downloads][downloads-image]][downloads-url]

[![Build Status][travis-image]][travis-url]

[![codecov][codecov-image]][codecov-url]



Native Koa 2 session middleware, inspired by and compatible with [koa-generic-session](https://github.com/koajs/generic-session). This can be used as a drop-in replacement for `koa-generic-session` in Koa 2.



This rewrite implements `koa-generic-session`'s essential interfaces, with around 100 lines of code in ES6. It supports existing session stores for `koa-generic-session`.



Version 4+ requires node 8+. Please use v3.0.4 for node versions older than 8.



## Minimum features and storage usage



This middleware guarantees the following:

- Minimum data generation and storage. No session data modification / pollution.

  - Neither a cookie nor a session store record is created unless session data gets populated by other middlewares.

  - Cookie options are not saved in the `ctx.session` object or session store (try to address [this concern](https://github.com/koajs/generic-session/issues/72)).

- Minimum updates on cookie and session store. Cookie and session store only get updated when session data has been changed.

  - When `ctx.session` gets updated (is a non-empty object), cookie and store data will be updated with new values and new expiration time (`maxAge`).

  - When `ctx.session` gets cleared ( `= {}` or `null` ), cookie and store data will be deleted.

  - If a session has not been updated within `maxAge`, its data will be expired.

- Minimum public interfaces and configuration options.

  - Cookie options: `maxAge`, `path`, `domain`, `secure`, `httpOnly`

  - Session interfaces: `session`, `sessionHandler { regenerateId() }`

  - Store interfaces: `get()`, `set()`, `destroy()`



## Installation



```shell

$ npm install koa-session-minimal

```



## Usage



```javascript

const Koa = require('koa')

const session = require('koa-session-minimal')

const redisStore = require('koa-redis')



const app = new Koa()



app.use(session({

  store: redisStore()

}))



// count middleware, increment when url = /add

app.use(async (ctx, next) => {

  ctx.session.count = ctx.session.count || 0

  if (ctx.path === '/add') ctx.session.count++



  await next()



  ctx.body = ctx.session.count

})



app.listen(3000)

```



## Interfaces



- session data via `ctx.session` (the same way as `koa-generic-session`)

- session methods via `ctx.sessionHandler`

  - `regenerateId()`: regenerate session id



## Options



- `key`: session cookie name and store key prefix

- `store`: session store

- `cookie`: cookie options, can be an object (static cookie options) or a function that returns an object (dynamic cookie options). Only `maxAge`, `path`, `domain`, `secure`, `httpOnly` are supported as option keys (see option details in [`cookies`](https://github.com/pillarjs/cookies) module).



## Session expiration



Default session has settings `cookie.maxAge = 0` for cookie and `ttl = ONE_DAY` for session store, means that a session will be expired in one of the following circumstances:

- A user close the browser window (transient cookie ends)

- Session data hasn't been updated within `ONE_DAY` (storage expires)



With settings that `cookie.maxAge > 0`, the `ttl` for store data will be always the same as `maxAge`.



## Dynamic session expiration (cookie options)



When setting `cookie` option to a plain object, all sessions will use the same cookie options. If a function is assigned to `cookie`, cookie options will be dynamically calculated at each (non-empty) session's saving stage.

For example, you can use an arrow function to set different `maxAge` for user and guest sessions, as below:

```javascript

session({

  cookie: ctx => ({

    maxAge: ctx.session.user ? ONE_MONTH : 0

  })

})

```



## Session security



Middlewares are recommended to call `sessionHandler.regenerateId()` during authentication state change (login). This middleware provides the essential interface, It will be other middleware's decision on when and how often they want to roll the session id.



> NOTE: Below is mostly copied from `koa-generic-session`'s README, because the two middlewares share the same store interfaces. Any store that implements `koa-generic-session`'s store interfaces should also work with `koa-session-minimal`. `koa-redis` is tested as an example in `test/store_redis.test.js`



## Session store



You can use any other store to replace the default MemoryStore, it just needs to follow this api:



- `get(sid)`: get session object by sid

- `set(sid, sess, ttl)`: set session object for sid, with a ttl (in ms)

- `destroy(sid)`: destroy session for sid



the api needs to return a Promise, Thunk, generator, or an async function.



## Stores presented



- [koa-redis](https://github.com/koajs/koa-redis) to store your session data with redis.

- [koa-mysql-session](https://github.com/tb01923/koa-mysql-session) to store your session data with MySQL.

- [koa-generic-session-mongo](https://github.com/freakycue/koa-generic-session-mongo) to store your session data with MongoDB.

- [koa-pg-session](https://github.com/TMiguelT/koa-pg-session) to store your session data with PostgreSQL.

- [koa-generic-session-rethinkdb](https://github.com/KualiCo/koa-generic-session-rethinkdb) to store your session data with ReThinkDB.

- [koa-sqlite3-session](https://github.com/chichou/koa-sqlite3-session) to store your session data with SQLite3.

- [koa-generic-session-sequelize](https://github.com/natesilva/koa-generic-session-sequelize) to store your session data with the [Sequelize](http://docs.sequelizejs.com/) ORM.



# License



  MIT



[npm-image]: https://img.shields.io/npm/v/koa-session-minimal.svg

[npm-url]: https://www.npmjs.com/package/koa-session-minimal

[downloads-image]: http://img.shields.io/npm/dm/koa-session-minimal.svg

[downloads-url]: https://www.npmjs.com/package/koa-session-minimal

[travis-image]: https://travis-ci.org/longztian/koa-session-minimal.svg?branch=master

[travis-url]: https://travis-ci.org/longztian/koa-session-minimal

[codecov-image]: https://codecov.io/gh/longztian/koa-session-minimal/branch/master/graph/badge.svg

[codecov-url]: https://codecov.io/gh/longztian/koa-session-minimal