fix: Unable to parse response body the throw the HTTP error

[TokugawaTakeshi]

Description

According the documentation,

If you want to return errors with specific error codes, there is an easy way:

@Get("/users/:id")
getOne(@Param("id") id: number) {

    const user = this.userRepository.findOneById(id);
    if (!user)
        throw new NotFoundError(`User was not found.`); // message is optional

    return user;
}

Now, when user won't be found with requested id, response will be with http status code 404 and following content:

{
  "name": "NotFoundError",
  "message": "User was not found."
}

Source

Unfortunately, when I tried to throw the BadRequestError, I can not access to response data:

According to response headers, the Content-Type has text/html; charset=utf-8 type:

Same as browser developer tools can not parse it, the text() method of fetch API fails.

Minimal code-snippet showcasing the problem

import {
  Controller,
  Post,
  BadRequestError
} from "routing-controllers";


@Controller()
export default class SampleController {

  @Post("/api/sample")
  protected sampleHandler(): void {
    throw new BadRequestError("Sample");
  }

}

Expected behavior

The response with content-type: application/json; charset=utf-8 header and following content will be submitted to client:

{
  "name": "BadRequestError",
  "message": "Sample"
}

Actual behavior

The response has content-type: text/html; charset=utf-8 header and non-parseable content.

[attilaorosz]

Could you try @JsonController instead of @Controller?

[TokugawaTakeshi]

@attilaorosz

Thank you for the answer.

Could you try @JsonController instead of @Controller?

I have tried @JsonController , but nothing has changed.
Well, even it works, my controllers returns both JSON and HTML, so it was not the solution.l

I am using option classTransformer: false, maybe it is related?
My application will not work if I'll enable it.

[attilaorosz]

I don't really understand how it could return both html and json. Could you setup a simple reproduction repo for this so I can check it?

[TokugawaTakeshi]

@attilaorosz

Could you setup a simple reproduction repo for this so I can check it?

It will take some some to boil down my app which is production-ready, but if you need to for investigation, I'll prepare it.
Please keep this issue opened.

I don't really understand how it could return both html and json.

Simply if MVC application also has REST API.

@Controller
class BlogPostController {

  /* === MVC ======================== */
  @View("views/BlogPost.hbs")
  protected renderBlogPostPage(): Promise<BlogPost> {
     // ... Transactions with DB
     return {
        // ...
     }
  }

  /* === REST ======================== */
  protected addBlogPost(): Promise<void> {
    // ... Transactions with DB
    // Once done frontend can redirect to blog post page thus does not need the response data
  }

}

[TokugawaTakeshi]

@attilaorosz

Sorry for keep you waiting.
Fortunately, the creating of reproduction have not took too much time, even I was not need to boil done my initial project.

Here is the reproduction:
https://github.com/TokugawaTakeshi/Issue-RoutingControllersErrorData

As you can see, there is still Content-Type: text/html; charset=utf-8 among the response headers while the response body is even not the HTML:

[attilaorosz]

Ok I think I understand your problem now.
The thing is, if you don't use @JsonController, the response type will not be set to json. If you would like to have a mixed response type controller you can do it manually.

Keep your view methods html, so @Controller is sufficient.

For the json methods, inject @Res() into the method params, constuct your response as it was a normal express response, then return the res object from the method.

  @Get('/api/sample')
  protected sampleHandlerJson(@Res() res: Response) {
    res.status(404);
    res.json();

    return res;
  }

  @Get('/api/sample/working')
  protected sampleHandlerJsonWithoutError(@Res() res: Response) {
    res.json({myParam: 'myValue'});

    return res;
  }

[attilaorosz]

Alternatively, if you only want to use json for errors, you can do this response handling in the error handler.