Pass file uploaded via HTTP POST to another API

Question

I have a Node.js (16.13.1) REST API using Express and one of my endpoints receives one or more uploaded files. The client (web app) uses FormData into which the files are appended. Once they're submitted to my API, the code there uses multer to grab the files from the request object.

Now I'm having trouble trying to send those same files to another API. multer attaches the files to req.files and each file object in that array has several properties one of which is buffer. I tried using the stream package's Duplex object to convert this buffer to a stream so that I could append the file to another FormData object, but when the server the second API is running on receives the request, I get an error from the web server saying that "a potentially dangerous request.form value was detected from the client.".

Any suggestions?

Answer 1

I am working on a nest project I was also facing this issue did some research and found that we need to create a Readable from the Buffer of that file and it's working for me.

// Controller
@UseInterceptors(FileInterceptor('file'))
async uploadFile(@UploadedFile() file: Express.Multer.File) {
   return this.apiservice.upload(file);
}

// Service
uploadFile(file: Express.Multer.File) {
    const readstream = Readable.from(file.buffer)
    console.log(readstream)
    const form = new FormData();
    form.append('file', file, { filename: extra.filename });

    const url = `api_endpoint`;

    const config: AxiosRequestConfig = {
       headers: {
         'Content-Type': 'multipart/form-data'
       },
    };
   return axios.post(url, form, config);
}