Skip to main content

Middleware

Middleware functions are pivotal in the request-response cycle of an ExpressoTS application, providing the capability to execute code, modify request and response objects, end the request-response cycle, or call the next middleware in the stack. It's essential to call next() to avoid request timeouts unless your middleware concludes the cycle.

ExpressoTS seamlessly integrates with Express middleware, enabling the use of its extensive ecosystem to enhance your application.

info

ExpressoTS fully supports Express middleware.

List of middlewares available​

Expressjs middlewares supported by ExpressoTS:

Middleware NameDescription
addBodyParserAdd body parser middleware to the application.
addCompressionAdd compression middleware to the application.
addCorsAdd cors middleware to the application.
addHelmetAdd helmet middleware to the application.
addCookieParserAdd cookie parser middleware to the application.
addCookieSessionAdd cookie session middleware to the application.
addSessionAdd session middleware to the application.
addServerStaticAdd static middleware to the application.
addRateLimitAdd rate limit middleware to the application.
addMorganAdd morgan middleware to the application.
addPassportAdd passport middleware to the application.
setMulterAdd multer middleware to the application.
addServeFaviconAdd serve favicon middleware to the application.
setErrorHandlerAdd error handler middleware to the application.

Adding middleware​

ExpressoTS application supports adding middleware globally to the application as well as per route. It offers all the middleware supported by Express Team out-of-the-box through the use of this.middleware property.

@provide(App)
export class App extends AppExpress {
    private middleware: IMiddleware;

    constructor() {
        super();
        this.middleware = container.get<IMiddleware>(Middleware);
    }

    protected configureServices(): void {
        this.middleware.addBodyParser();
        this.middleware.addCors();
        this.middleware.addHelmet();
    }
}
caution

If you add a middleware that is not installed as dependency, the application will throw a warning message and continue to run.

Adding global middleware​

Middlewares can be added globally using the App class through the this.middleware property, using the out-of-the-box middleware list provided by Express Team:

protected configureServices(): void {
        this.middleware.addBodyParser();
        this.middleware.addCors();
        this.middleware.addHelmet();
    }

Using addMiddleware method​

For any other middleware, or a custom middleware, you can add it using the this.middleware.addMiddleware() method. Using the addMiddleware method, you can add any middleware from NPM Registry, custom Expressjs middleware or a custom middleware.

NPM Registry middleware:

this.middleware.addMiddleware(cors());

Creating expressjs middleware​

function myMiddleware(req: Request, res: Response, next: NextFunction) {
    // Do something
    next();
}
this.middleware.addMiddleware(myMiddleware);

Creating expressots middleware​

Custom ExpressoTS middleware:

class CustomMiddleware extends ExpressoMiddleware {
    use(req: Request, res: Response, next: NextFunction): void | Promise<void> {
        // Do something
        next();
    }
}
this.middleware.addMiddleware(new CustomMiddleware());

Route Middleware​

Middlewares can be added per route in the App class through the this.middleware.addMiddleware() method. You can add any middleware from NPM Registry, custom Expressjs middleware or a custom middleware.

this.middleware.addMiddleware({ path: "/api", middlewares: [] });
info

Each route can have multiple middlewares.

Adding middleware to a specific route​

Or you add a middleware to a specific route in the Controller class through the @controller() and/Or http Method decorators.

@controller("/")
export class AppController {
    @Post("", express.json())
    execute() {
        return "Hello World";
    }
}

Adding middleware to all routes in a controller​

If you want to apply a middleware to all routes under a specific controller, you can add it to the @controller() decorator.

@controller("/app", express.json())
export class AppController {
    @Post("/create")
    createApp() {
        return "Create App";
    }

    @Patch("/update")
    updateApp() {
        return "Update App";
    }
}

Example of custom expressoTS middleware​

To create a custom middleware, you need to extend the ExpressoMiddleware class and implement the use method.

class CustomMiddleware extends ExpressoMiddleware {
    private isOn: boolean;

    constructor(isOn: boolean) {
        super();
        this.isOn = isOn;
    }

    use(req: Request, res: Response, next: NextFunction): void | Promise<void> {
        // Do something
        if (this.isOn) {
            next();
        } else {
            res.status(403).send("Forbidden");
        }
    }
}

Custom middleware allows you to pass parameters to the constructor and use them as options in the use method of your middleware.

View all middlewares pipeline​

You can view all the middlewares added to the application using the this.middleware.viewMiddlewarePipeline() method.

View Middleware Pipeline

Use ExpressoTS CLI to scaffold a custom middleware.

CLI command to scaffold a custom middleware:

expressots g mi <<middleware-name>>

Support the project​

ExpressoTS is an MIT-licensed open source project. It's an independent project with ongoing development made possible thanks to your support. If you'd like to help, please consider: