Session 创建原理, 流程

这个库的Session内容是放在内存中的Store对象中的. 而这个Store本质上来说就是一个键值对存储。 这个库使用的时候有个默认的key是从Cookie中读取Store中的key的值，然后根据这个key的值 去获取真正的session内容。

这个库的实现, 是在没回读取成功session之后，会在返回的时候再通过uuid重新生成一个session key, 存储 到客户端的Cookie中。

ctx.session = await opts.store.get(id);
//....

await next();
//...
let sid = await opts.store.set(ctx.session, Object.assign({}, opts, {sid: id}));
ctx.cookies.set(opts.key, sid, opts);

koa-session2

Middleware for Koa2 to get/set session use with custom stores such as Redis or mongodb with Babel

If you are not using babel in your projects, maybe you can try this version without babel.

Install

npm install koa-session2

Usage

import Koa from "koa";
import session from "koa-session2";

const app = new Koa();

app.use(session({
    key: "SESSIONID",   //default "koa:sess"
}));

Custom Stores

Store.js

import Redis from "ioredis";
import {Store} from "koa-session2";

export default class RedisStore extends Store {
    constructor() {
        super();
        this.redis = new Redis();
    }

    async get(sid) {
        return await this.redis.get(`SESSION:${sid}`);
    }

    async set(session, opts) {
        if(!opts.sid) {
            opts.sid = this.getID(24);
        }
        await this.redis.set(`SESSION:${opts.sid}`, session);
        return opts.sid;
    }

    async destroy(sid) {
        return await this.redis.del(`SESSION:${sid}`);
    }
}

main.js

import Koa from "koa";
import session from "koa-session2";
import Store from "./Store.js";

const app = new Koa();

app.use(session({
    store: new Store()
}));

app.use(ctx => {
    let user = ctx.session.user;

    ctx.session.view = "index";
});

Options

Most options based on cookies

• key: a string for store session id in cookie

• store: a class for custom store (extend {Store}, func: #get(sid), #set(session, opts), #destory(sid))

• maxAge: a number representing the milliseconds from Date.now() for expiry

• expires: a Date object indicating the cookie's expiration date (expires at the end of session by default).

• path: a string indicating the path of the cookie (/ by default).

• domain: a string indicating the domain of the cookie (no default).

• secure: a boolean indicating whether the cookie is only to be sent over HTTPS (false by default for HTTP, true by default for HTTPS).

• httpOnly: a boolean indicating whether the cookie is only to be sent over HTTP(S), and not made available to client JavaScript (true by default).

• signed: a boolean indicating whether the cookie is to be signed (false by default). If this is true, another cookie of the same name with the .sig suffix appended will also be sent, with a 27-byte url-safe base64 SHA1 value representing the hash of cookie-name=cookie-value against the first Keygrip key. This signature key is used to detect tampering the next time a cookie is received.

• overwrite: a boolean indicating whether to overwrite previously set cookies of the same name (false by default). If this is true, all cookies set during the same request with the same name (regardless of path or domain) are filtered out of the Set-Cookie header when setting this cookie.

License

MIT