Use formidable's PersistentFile with FormData and fetch

Question

I'm running a small api with nuxt3/nitro. It works like a proxy between my webapp and my regular api. So my nitro api receives files, I read them from the request using Formidable, and they get saved in formidable's PersistentFileinstances.

Now I need to put these files in a regular formData.append syntax, so I can use the fetch api to send a post containing these files in the formData.

How can I do this? If I just put the file like formData.append('name', persistentFileInstance); it says it isn't recognized as a file. So I'm kinda lost on how should I transform this instance.

Here's a console.log of my file:

addImage.post.ts called with this content {                                                                                                       19:33:43
  photo: [
    PersistentFile {
      _events: [Object: null prototype],
      _eventsCount: 1,
      _maxListeners: undefined,
      lastModifiedDate: 2023-01-07T22:33:43.127Z,
      filepath: '/tmp/0d0c99ee783bfe790d86da001',
      newFilename: '0d0c99ee783bfe790d86da001',
      originalFilename: 'Screenshot from 2023-01-04 09-04-32.png',
      mimetype: 'image/png',
      hashAlgorithm: false,
      size: 110657,
      _writeStream: [WriteStream],
      hash: null,
      [Symbol(kCapture)]: false
    }
  ]
}

Answer 1

I fixed it by creating a buffer from the local file path, then a Blob instance, then appending the Blob to the FormData. Here's my code:

import { readFiles } from 'h3-formidable'
import { Blob } from "buffer";
import fs from "fs";

//...

  let buffer = fs.readFileSync(thisPhoto.filepath);
  let blob = new Blob([buffer]);
  
  var form = new FormData(); //this is default FormData instance, not the custom package
  form.append('photo', blob);