Add koa-router's Router to koa's Context (#27472)

types/koa-router/index.d.ts

@@ -3,6 +3,7 @@
 // Definitions by: Jerry Chin <https://github.com/hellopao>
 //                 Pavel Ivanov <https://github.com/schfkt>
 //                 JounQin <https://github.com/JounQin>
+//                 Romain Faust <https://github.com/romain-faust>
 // Definitions: https://github.com/hellopao/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -51,6 +52,10 @@ declare namespace Router {
          * url params
          */
         params: any;
+        /**
+         * the router instance
+         */
+        router: Router;
     }
 
     export interface IMiddleware {

types/koa-router/koa-router-tests.ts

@@ -8,21 +8,27 @@ const router = new Router({
 });
 
 router
-  .param('id', function(id, ctx, next) {
-    next();
-  })
-  .get('/', function (ctx, next) {
-    ctx.body = 'Hello World!';
-  })
-  .post('/users', function (ctx, next) {
-    // ...
-  })
-  .put('/users/:id', function (ctx, next) {
-    ctx.body = ctx.params.id;
-  })
-  .del('/users/:id', function () {
-    // ...
-  });
+    .param('id', function (id, ctx, next) {
+        next();
+    })
+    .get('/', function (ctx, next) {
+        ctx.body = 'Hello World!';
+    })
+    .get('/users/:id', function (ctx, next) {
+        ctx.body = ctx.router.url('user-accounts', { id: ctx.params.id })
+    })
+    .get('user-accounts', '/users/:id/accounts', function (ctx, next) {
+        // ...
+    })
+    .post('/users', function (ctx, next) {
+        // ...
+    })
+    .put('/users/:id', function (ctx, next) {
+        ctx.body = ctx.params.id;
+    })
+    .del('/users/:id', function () {
+        // ...
+    });
 
 router.get('user', '/users/:id', function (ctx) {
     ctx.body = "sdsd";