add context to external store .get() and .set() options params

Readme.md

@@ -111,9 +111,9 @@ console.log('listening on port 3000');
 
   You can store the session content in external stores (Redis, MongoDB or other DBs) by passing `options.store` with three methods (these need to be async functions):
 
-  - `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
+  - `get(key, maxAge, { rolling, ctx })`: get session object by key
+  - `set(key, sess, maxAge, { rolling, changed, ctx })`: set session object for key, with a `maxAge` (in ms)
+  - `destroy(key, {ctx})`: destroy session for key
 
 
   Once you pass `options.store`, session storage is dependent on your external store -- you can't access the session if your external store is down. **Use external session stores only if necessary, avoid using session as a cache, keep the session lean, and store it in a cookie if possible!**

lib/context.js

@@ -87,7 +87,7 @@ class ContextSession {
       return;
     }
 
-    const json = await this.store.get(externalKey, opts.maxAge, { rolling: opts.rolling });
+    const json = await this.store.get(externalKey, opts.maxAge, { ctx, rolling: opts.rolling });
     if (!this.valid(json, externalKey)) {
       // create a new `externalKey`
       this.create();
@@ -284,7 +284,7 @@ class ContextSession {
     const key = opts.key;
     const externalKey = this.externalKey;
 
-    if (externalKey) await this.store.destroy(externalKey);
+    if (externalKey) await this.store.destroy(externalKey, { ctx });
     ctx.cookies.set(key, '', opts);
   }
 
@@ -320,6 +320,7 @@ class ContextSession {
       }
       await this.store.set(externalKey, json, maxAge, {
         changed,
+        ctx: this.ctx,
         rolling: opts.rolling,
       });
       if (opts.externalKey) {

test/store_with_ctx.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const sessions = {};
+
+module.exports = {
+  async get(key, maxAge, options) {
+    // check access to options.ctx
+    options.ctx.state.test = 'get';
+    return sessions[key];
+  },
+
+  async set(key, sess, maxAge, options) {
+    // check access to options.ctx
+    options.ctx.state.test = 'set';
+    sessions[key] = sess;
+  },
+
+  async destroy(key, options) {
+    // check access to options.ctx
+    options.ctx.state.test = 'destroyed';
+    sessions[key] = undefined;
+  },
+};

test/store_with_ctx.test.js

@@ -0,0 +1,81 @@
+'use strict';
+
+const Koa = require('koa');
+const request = require('supertest');
+const session = require('..');
+const store = require('./store_with_ctx');
+
+describe('Koa Session External Store methods can acceess Koa context', () => {
+  let cookie;
+
+  describe('new session', () => {
+    describe('when not accessed', () => {
+      it('should not set ctx.state.test variable', async () => {
+        const app = App();
+
+        request(app.callback())
+          .get('/')
+          .expect('undefined');
+      });
+    });
+
+    describe('when populated', () => {
+      it('should set ctx.state.test variable', done => {
+        const app = App();
+
+        app.use(async ctx => {
+          if (ctx.path === '/set') ctx.session = { foo: 'bar' };
+        });
+
+        request(app.listen())
+        .get('/set')
+        .expect(200, (err, res) => {
+          if (err) return done(err);
+          cookie = res.header['set-cookie'].join(';');
+          res.text.should.equal('set');
+          done();
+        });
+      });
+    });
+
+    describe('when accessed', () => {
+      it('should access ctx.state.test variable', async () => {
+        const app = App();
+
+        request(app.callback())
+          .get('/')
+          .set('Cookie', cookie)
+          .expect('get');
+      });
+    });
+
+    describe('session destroyed', () => {
+      it('should access ctx.state.test variable', async () => {
+        const app = App();
+
+        app.use(async ctx => {
+          if (ctx.path === '/destroy') ctx.session = null;
+        });
+
+        request(app.callback())
+          .get('/destroy')
+          .set('Cookie', cookie)
+          .expect('destroyed');
+      });
+    });
+  });
+});
+
+function App(options) {
+  const app = new Koa();
+  app.keys = [ 'a', 'b' ];
+  options = options || {};
+  options.store = store;
+  app.use(async (ctx, next) => {
+    await next();
+    ctx.body = ctx.state.test === undefined ? 'undefined' : ctx.state.test;
+  });
+
+  app.use(session(options, app));
+  return app;
+}