What is meta-controller?

meta-controller is a library for creating NodeJs REST APIs using TypeScript decorators. It is a wrapper for the popular express framework. It's designed to be a lightweight alternative to NestJs.

Installation

Install the meta-controller package from npm.
npm install meta-controller

Basic Usage

Create a REST API controller by using the JsonController(<route>) decorator and define routes by using the @Route(<http method>, <path>) decorator. Routes can be synchronous or asynchronous. Route paramaters are automatically transformed (meta-transformer) and validated (meta-validator).

@JsonController("/basic")
class WidgetController {
    @Route(HttpMethod.GET)
    get(): Widget {
        return testWidget;
    }
}

const expressApp = express();
MetaController.useExpressServer(expressApp, {
    isUseCors: true,
    controllerClassTypes: [
        WidgetController
    ]
});
apiServer = http.createServer(expressApp);
apiServer.listen(4500);

Initialization

Pass an instance of express to MetaController.useExpressServer() to initialize meta-controller.

const expressApp = express();
MetaController.useExpressServer(expressApp, {
    // options
});

The following initialization options are available.

Option	Description
isDebug	Log any errors to stdout
routePrefix	Add a global route prefix (e.g. /api)
isUseCors	Add CORS to all routes
isSaveRawBody	Add the raw body to the request object (request.rawBody)
controllerClassTypes	An array of class controllers that will be added as express routes)
authorizationHandler	A user supplied function that determines if the request has been authorized
currentUserHandler	A user supplied function that retrieves the user (if any) of the current request
customErrorHandler	A global custom error handler
globalMiddleware	Any optional global middleware

Route Parameters

Controllers may accept all standard REST type parameters. Parameters are automatically transformed or cast to the specified type.

HTTP Request Body

@Route(HttpMethod.POST, "/body")
myRoute(@Body() widget: Widget) {
    // ... business logic
}

Route Parameters

// Example: https://localhost/api/param/5
@Route(HttpMethod.GET, "/param/:id")
myRoute(@Param("id") id: number) {
    // ... business logic    
}

Route Query Parameters

// Example: https://localhost/api/query-param?myQueryParam=test
@Route(HttpMethod.POST, "/query-param")
myRoute(@QueryParam("myQueryParam") myQueryParam: string) {
    // ... business logic    
}

HTTP Request Headers

@Route(HttpMethod.GET, "/header-param")
myRoute(@HeaderParam("TestHeader") testHeader: string) {
    // ... business logic    
}

Authorization

You can require authorization on a per-controller basis by specifying an authorizationHandler() and using the @Authorization() decorator.

const expressApp = express();
MetaController.useExpressServer(expressApp, {
    authorizationHandler: (request, response, roles): boolean => {
        // ... business logic
        // Return true for authorized, false for unauthorized
        return true;
    }
});

@Authorize(["Admin"])
@JsonController("/secure")
class SecureController {
    @Route(HttpMethod.GET, "/protected-route")
    myRoute() {
        // ... business logic
    }
}

If you also add a currentUserHandler() you can inject the current user using the CurrentUser() decorator.

class User {
    userName: string = "TestUser";
}
const testUser = new User();

const expressApp = express();
MetaController.useExpressServer(expressApp, {
    currentUserHandler: (request, response): User => {
        // ... business logic
        return testUser;
    }
});

@Route(HttpMethod.GET, "/current-user")
getCurrentUser(@CurrentUser() currentUser: User): User {
    // ... business logic
    return currentUser;
}

Error Handling

You can throw errors along with associated HTTP error codes.

@Authorize(["Admin"])
@JsonController("/secure")
class SecureController {
    @Route(HttpMethod.GET, "/protected-route")
    myRoute() {
        throw new HttpError(HttpStatus.UNAUTHORIZED, "Unauthorized request");
    }
}

If no HTTP error code is specified then meta-controller defaults to using HTTP status 500 (INTERNAL_SERVER_ERROR).

@Route(HttpMethod.POST, "/body")
myRoute(@Body() widget: Widget) {
    // Returns HTTP status 500 - INTERNAL_SERVER_ERROR
    throw new Error("An unknown error occurred");
}

Decorator Reference

Decorator	Type	Description
@Authorize()	Class	Controller requires authorization
@JsonController()	Class	Create a JSON controller
@Body()	Parameter	Inject a JSON body parameter
@CurrentUser()	Parameter	Inject the current user
@EncodedJwtToken()	Parameter	Inject the encoded JWT token string
@HeaderParam()	Parameter	Inject a header from the HTTP request
@Param()	Parameter	Inject a route parameter (e.g. /user/:id)
@QueryParam()	Parameter	Inject a query parameter (e.g. /route?my-param=test)
@Request()	Parameter	Inject the entire request object
@Response()	Parameter	Inject the entire response object
@Route(<http method, path>)	Property	Define a route on the controller