disintegratorD
Deno•3y ago•
36 replies
disintegrator

Streaming large files with fetch and FormData

Hi, I'm trying to find a way to build multiplart/form-data requests in Deno that contain large files. Ideally, I'll like these requests and the underlying files to be streamed out instead of needing to read the whole file into memory and adding them as parts to the request. I can't seem to find a built-in API for acquiring a Blob-like file handle. I also tried using 
npm:fetch-blob/from.js
 but that isn't compatible with Deno. Compared to other platforms:
Node.js v20+: the 
fs.openAsBlob
 function in 
node:fs
 can return a web 
File
 backed by the file system
Bun: The 
Bun.file
 function also returns a web 
File
 backed by the file system


import { fileFrom } from "npm:fetch-blob/from.js";

async function run() {
  const file = await fileFrom("./sample.txt");
  const fd = new FormData();
  fd.append("file", file);

  const res = await fetch("https://httpbin.org/anything/upload", {
    method: "POST",
    body: fd,
  });

  console.log(await res.json());
}

run();


Any suggestions on how I can make this work in Deno?
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