Create generic createServer function

Author: MichalLytek

src/driver/BaseDriver.ts

@@ -19,6 +19,11 @@ export abstract class BaseDriver {
     // Public Properties
     // -------------------------------------------------------------------------
 
+    /**
+     * Reference to the underlying framework app object.
+     */
+    app: any;
+
     /**
      * Indicates if class-transformer should be used or not.
      */

src/driver/express/ExpressDriver.ts

@@ -28,6 +28,7 @@ export class ExpressDriver extends BaseDriver {
     constructor(public express?: any) {
         super();
         this.loadExpress();
+        this.app = this.express;
     }
 
     // -------------------------------------------------------------------------

src/driver/koa/KoaDriver.ts

@@ -29,6 +29,7 @@ export class KoaDriver extends BaseDriver {
         super();
         this.loadKoa();
         this.loadRouter();
+        this.app = this.koa;
     }
 
     // -------------------------------------------------------------------------

src/index.ts

@@ -1,4 +1,5 @@
 import {CustomParameterDecorator} from "./CustomParameterDecorator";
+import {BaseDriver} from "./driver/BaseDriver";
 import {ExpressDriver} from "./driver/express/ExpressDriver";
 import {KoaDriver} from "./driver/koa/KoaDriver";
 import {MetadataArgsStorage} from "./metadata-builder/MetadataArgsStorage";
@@ -110,40 +111,46 @@ export function getMetadataArgsStorage(): MetadataArgsStorage {
  * Registers all loaded actions in your express application.
  */
 export function useExpressServer<T>(expressApp: T, options?: RoutingControllersOptions): T {
-    createExecutor(new ExpressDriver(expressApp), options || {});
-    return expressApp;
+    const driver = new ExpressDriver(expressApp);
+    return createServer(driver, options);
 }
 
 /**
  * Registers all loaded actions in your express application.
  */
 export function createExpressServer(options?: RoutingControllersOptions): any {
     const driver = new ExpressDriver();
-    createExecutor(driver, options || {});
-    return driver.express;
+    return createServer(driver, options);
 }
 
 /**
  * Registers all loaded actions in your koa application.
  */
 export function useKoaServer<T>(koaApp: T, options?: RoutingControllersOptions): T {
-    createExecutor(new KoaDriver(koaApp), options || {});
-    return koaApp;
+    const driver = new KoaDriver(koaApp);
+    return createServer(driver, options);
 }
 
 /**
  * Registers all loaded actions in your koa application.
  */
 export function createKoaServer(options?: RoutingControllersOptions): any {
     const driver = new KoaDriver();
-    createExecutor(driver, options || {});
-    return driver.koa;
+    return createServer(driver, options);
+}
+
+/**
+ * Registers all loaded actions in your application using selected driver.
+ */
+export function createServer<T extends BaseDriver>(driver: T, options?: RoutingControllersOptions): any {
+    createExecutor(driver, options);
+    return driver.app;
 }
 
 /**
  * Registers all loaded actions in your express application.
  */
-export function createExecutor(driver: Driver, options: RoutingControllersOptions): void {
+export function createExecutor<T extends BaseDriver>(driver: T, options: RoutingControllersOptions = {}): void {
 
     // import all controllers and middlewares and error handlers (new way)
     let controllerClasses: Function[];