File field is not being included in @Body decorator in NestJS

Question

I'm trying to build a simple route where the user will post few text data along with a file. Let's say a task where the properties will be title, description, and file. I have created a DTO for this as follows:-

export class CreateTaskDto {
  title: string;
  description: string;
  file: any
}

And here is the storage.config.ts

export const storage = diskStorage({
  destination: "./uploads",
  filename: (req, file, callback) => {
    callback(null, generateFilename(file));
  }
});

function generateFilename(file) {
  const filename = file.originalname
  const ext = filename.split(".").pop()
  return `${Date.now()}_${filename}`;
}

The tasks.controller.ts

@Post()
@UseInterceptors( FileInterceptor( "file", { storage }))
async createNewTask(@UploadedFile() file, @Body() dto: CreateTaskDto) {
  /*
   here is the dto I received:
   {
      "title": "Task Title",
      "description": "Task Description"
   }

   You can see that the file field is not being added to the dto
   */
}

The file field data is not included in the @Body decorator variable dto . I know I can access the file data via the file variable but is there any way to instruct nest to include the file value into the @Body decorator?

Thanks

Answer 1

This is how multer works, it takes the uploaded files and attaches them to req.file or req.files depending on if one or many were sent. You could create a custom decorator to merge the req.body and req.file together if you wanted, but generally this isn't something Nest does, but the underlying package itself.