Question: example of how to use error middleware? about node-decorators HOT 10 CLOSED

Hi @markkelsall no worries :)

Error middleware is a special middleware that needs to be registered via ERROR_MIDDLEWARE token, like so:

import { ErrorMiddleware, ERROR_MIDDLEWARE } from '@decorators/express';

@Injectable()
class ServerErrorMiddleware implements ErrorMiddleware {
  public use(error: Error, request: Request, response: Response, next: NextFunction) {
    next();
  }
}

Container.provide([
  { provide: ERROR_MIDDLEWARE, useClass: ServerErrorMiddleware }
]);

Error middleware is different to other middlewares cause it has error as a first argument and that's why it's treated a bit differently. Here's the example how to use it in my demo project https://github.com/serhiisol/decorators-server/blob/master/src/middleware/server-error.ts

from node-decorators.

Great, thanks. In your inline example, what is Container? How does it get attached to an express instance? Or is it just a case of having it listed in your middleware stack on a method/controller and it only gets called if there was an error thrown/not handled?

In your demo project, the server error middleware doesn't seem to be referenced?

from node-decorators.

Container is an export from @decorators/di package that @decorators/express uses underneath.
Yes error middleware gets called only when error happens. Take a look at the whole repository as a reference.

from node-decorators.

Thanks, I had a closer look at your demo repo and it makes sense that you just set up the middleware but still don't see how the server app instance knows to use it as app and Container don't know about each other?

When pulled your decorators-server repo down, I couldn't get it to run, nor could I make error middleware trigger when I purposefully threw an error in one of my controllers.

from node-decorators.

Here's the app file - https://github.com/serhiisol/decorators-server/blob/master/src/app.ts

import { Container } from '@decorators/di';
import { attachControllers, ERROR_MIDDLEWARE } from '@decorators/express';
import { json, urlencoded } from 'body-parser';
import * as express from 'express';
import * as cors from 'cors';
import { initialize as initializePassport } from 'passport';

import { configurePassport, ServerErrorMiddleware } from './middleware';
import { StatusController, AuthController } from './api';

export function init(): express.Application {
  const app: express.Express = express();

  configurePassport();

  app.use(json());
  app.use(urlencoded({ extended: false }));
  app.use(initializePassport());
  app.use(cors());

  Container.provide([
    { provide: ERROR_MIDDLEWARE, useClass: ServerErrorMiddleware }
  ]);

  attachControllers(app, [
    StatusController,
    AuthController
  ]);

  return app;
}

from node-decorators.

Ok understand how they reference each other now - https://github.com/serhiisol/node-decorators/blob/master/express/src/express.ts#L14
However, it doesn't seem to work for me:

@Controller("/TestDecorator")
export class TestDecoratorController {
	@Get("/:id")
	getData(@DecoratorResponse() res, @Params("id") id: string): any {
		console.log("id", id);
		throw new Error("argh");
		// res.status(200).send({
		// 	id,
		// 	message: "hello"
		// });
	}
}

class ServerErrorMiddleware implements ErrorMiddleware {
	use(error: Error, request: Request, response: Response, _next: NextFunction) {
		console.log("caught this error", error.message);
		response.status(200).json({ message: "error" });
	}
}

Container.provide([{ provide: ERROR_MIDDLEWARE, useValue: ServerErrorMiddleware }]);

attachControllers(app, [TestDecoratorController]);

I'm expecting the response to the browser to be a json object with the message "error" but I'm just getting the native error being thrown back

from node-decorators.

Yes, based on the snippet above, that should be everything right? However the response is the error that is thrown in the controller rather than error middleware code

from node-decorators.

Hm, must be a bug. I'm going to fix it now.

from node-decorators.

This issue must have appeared with the latest release. With async providers introduced in the latest di package error middleware is applied before handlers. I'll prepare a release in a bit.

from node-decorators.

Pushed new version.

from node-decorators.