feat: support options.externalKey

Readme.md

@@ -114,6 +114,13 @@ console.log('listening on port 3000');
 
   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.
 
+### Custom External Key 
+
+  External key is used the cookie by default, but you can use `options.externalKey` to customize your own external key methods. `options.externalKey` with two methods:
+
+  - `get(key, opts, ctx)`: get the external key
+  - `set(key, value, opts, ctx)`: set the external key
+
 ### Session#isNew
 
   Returns __true__ if the session is new.

index.js

@@ -86,6 +86,13 @@ function formatOpts(opts) {
     assert(is.function(store.destroy), 'store.destroy must be function');
   }
 
+  const externalKey = opts.externalKey;
+
+  if (externalKey) {
+    assert(is.function(externalKey.get), 'externalKey.get must be function');
+    assert(is.function(externalKey.set), 'externalKey.set must be function');
+  }
+
   const ContextStore = opts.ContextStore;
   if (ContextStore) {
     assert(is.class(ContextStore), 'ContextStore must be a class');

lib/context.js

@@ -69,9 +69,14 @@ class ContextSession {
     debug('init from external');
     const ctx = this.ctx;
     const opts = this.opts;
-
-    const externalKey = ctx.cookies.get(opts.key, opts);
-    debug('get external key from cookie %s', externalKey);
+    let externalKey;
+    if (opts.externalKey) {
+      externalKey = opts.externalKey.get(opts.key, opts, ctx);
+      debug('get external key from custom %s', externalKey);
+    } else {
+      externalKey = ctx.cookies.get(opts.key, opts);
+      debug('get external key from cookie %s', externalKey);
+    }
 
     if (!externalKey) {
       // create a new `externalKey`
@@ -264,7 +269,11 @@ class ContextSession {
         changed,
         rolling: opts.rolling,
       });
-      this.ctx.cookies.set(key, externalKey, opts);
+      if (opts.externalKey) {
+        opts.externalKey.set(key, externalKey, opts, this.ctx);
+      } else {
+        this.ctx.cookies.set(key, externalKey, opts);
+      }
       return;
     }
 

test/externalKey.test.js

@@ -0,0 +1,64 @@
+'use strict';
+
+const Koa = require('koa');
+const request = require('supertest');
+const assert = require('assert');
+const session = require('..');
+const store = require('./store');
+const TOKEN_KEY = 'User-Token';
+
+describe('Koa Session External Key', () => {
+  describe('when the external key set/get is invalid', () => {
+    it('should throw a error', () => {
+      try {
+        new App({
+          externalKey: {},
+        });
+      } catch (err) {
+        assert.equal(err.message, 'externalKey.get must be function');
+      }
+    });
+  });
+
+  describe('custom get/set external key', () => {
+    it('should still work', done => {
+      const app = App();
+
+      app.use(async function(ctx) {
+        if (ctx.method === 'POST') {
+          ctx.session.string = ';';
+          ctx.status = 204;
+        } else {
+          ctx.body = ctx.session.string;
+        }
+      });
+
+      const server = app.listen();
+
+      request(server)
+        .post('/')
+        .expect(204, (err, res) => {
+          if (err) return done(err);
+          const token = res.get(TOKEN_KEY);
+          request(server)
+            .get('/')
+            .set(TOKEN_KEY, token)
+            .expect(';', done);
+        });
+    });
+  });
+});
+
+function App(options) {
+  const app = new Koa();
+  app.keys = [ 'a', 'b' ];
+  options = options || {};
+  options.store = store;
+  options.key = TOKEN_KEY;
+  options.externalKey = options.externalKey || {
+    get: (key, opts, ctx) => ctx.get(key),
+    set: (key, value, opts, ctx) => ctx.set(key, value),
+  };
+  app.use(session(options, app));
+  return app;
+}