NestJS Streaming Files technique not working

Question

I am trying to stream CSV file using NestJS Streaming Files technique, but the request seems to be stuck. Am I missing something here?

Sample code snippet:

import {StreamableFile} from '@nestjs/common';
import * as fs from 'fs';

@Get('csv')
csvStream(
  @Req() req: Request,
  @Res() res: Response,
): StreamableFile {
  const file = 'test.csv';
  const readStream = fs.createReadStream(file);
  readStream.on('data', (chunk) => console.log(chunk));  <--- the data log gets printed
  readStream.on('finish', () => console.log('done'));
  return new StreamableFile(readStream);
}

The data log gets printed (check statement - readStream.on('data', (chunk) => console.log(chunk))), and output is similar to below:

<Buffer 23 4a 45 67 11 97 ... 1022 more bytes>

and the request stays stuck in this state.

Answer 1

Following worked for me, locally...

import { Controller, Get, Req, Response, StreamableFile } from '@nestjs/common';
import * as fs from 'fs';
import * as path from 'path';

@Controller()
export class FileController {
    @Get('csv')
    csvStream(@Req() req, @Response({ passthrough: true }) res): StreamableFile {
        res.set({
            'Content-Type': 'text/plain'
        });

        const file = path.join(__dirname, 'test.csv');
        const readStream = fs.createReadStream(file);
        readStream.on('data', (chunk) => console.log(chunk)); // <--- the data log gets printed
        readStream.on('end', () => console.log('done'));
        readStream.on('error', (err) => { console.error(err); });

        return new StreamableFile(readStream);
    }
}

Please mind the { passthrough: true }. That's what made me get a response, so seems quite important!!!