How do dynamic redirect?

[pquerner]

Hello!

I have a route which create a model. If checks succeeds and the model could be saved to the database, I want to render a template.
If it fails, I want it to render a different template.

Like so:

@Controller('/pn')
export class PushNotificationsController extends BaseController {

@Post('/add')
    async createdOrError(@Res() response: Response, @Req() request: Request, @Body() pn: PushNotificationCreationAttributes) {
// ..

try {
            // save model
        } catch (error) {
            //todo: render error
            console.error(error);
            response.render('page/error.njk', {...});
            return;
        }
        return response.render('page/pn/created.njk', {...});

}

I have tried response.render(...) return;. but also direct return response render(...).

Getting error

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

[attilaorosz]

According to the docs, the render method does not return anything, it just sends the response internally. The problem with this is that routing-controllers will try to return whatever your controller returns, resulting in a 'double response'. However, if you return the response object itself, routing-controller will not try to do any additional response writing. Please try

response.render(...);
return response;

[attilaorosz]

Do you happen to have any middleware that runs after the controller? Or do you have a route that also matches your target route? If the response object is returned the .next method is called on response.
Another possible cause could be that you write the response in a before middleware and thats why the render fails.

[pquerner]

I use a middleware for session handling, and to resolve files from a "public" directory.

...use(express.static('public'));
...use(
            session({
                // ...
            })
        )

In the controller file no other routes are defined (that GET /test is all there is), nor any other middlewares.

The full controller file looks like that:

import {Controller, Get, Req, Res} from "routing-controllers";
import {Request, Response} from "express";

@Controller('/test')
export class TestController {
    @Get('/test')
    test(@Res() response: Response, @Req() request: Request) {
        console.log("test");
        if(false) {
            console.log("test2");
            response.render('page/empty.njk');
            return response;
        }
        console.log("test3");

        response.render('page/register.njk');
        return response;
    }
}

[attilaorosz]

Could you create a repro repo so I can try to debug this? According to the stacktrace, the error is originating from the default express error handler.

[pquerner]

You're right. I've setup a bare-bones clean repo with and it works there just fine.
I'll keep digging and update here when I find something.

[pquerner]

So far I havent found anything, but I added empty middleware and the error went away:

        useExpressServer(App.expressInstance, {
            controllers: [path.join(__dirname + '/controllers/*Controller.js')],
        });
        App.expressInstance.use(function(req, res, next) { // <-- without this the "ERR_HTTP_HEADERS_SENT" happens (Oô)
            next();
        });