React Simple S3 Uploader

Upload.tsx

import React, {useState} from "react";
import axios from "axios";
import config from "../config"

const endpoint = config.apiGateway.URL;

export const Upload = () => {

  const [file, setFile] = useState<File | undefined>()

  const onFormSubmit = (e: any) => {
    e.preventDefault() // Stop form submit
    if (file) {
      fileUpload(file).then((response) => {
        console.log(response.data);
      })
    }
  }

  const onChange = (e: any) => {
    setFile(e.target.files[0]);
  }

  const fileUpload = async (file: File) => {
    return axios.get(`${endpoint}`).then((res) => {
      console.log(res.data);
      const url = res.data.url;
      const config = {
        headers: {
          'content-type': file.type
        }
      }
      return axios.put(url, file, config)
    })
  }

  return (
    <form onSubmit={onFormSubmit}>
      <input type="file" onChange={onChange}/>
      <button type="submit">Upload</button>
    </form>
  )
}

Hi Felipe,

I'm using Scala with Http4s, along with the awscala.s3.S3 package to make S3 Java lib a little less verbose to use. The main thing that the backend is doing above is providing short-lived signed URL and returning that in a JSON response for the client to use, so that it can upload to S3 directly without passing through my api/backend server.

For example:
val url = s3.generatePresignedUrl(BUCKET, key, exp, HttpMethod.PUT)

And pass that url val back in some json response (e.g., { url: string } above) at which the client can use it here (line 33):
return axios.put(url, file, config)

Honestly, most of the magic/work is just setting up the AWS S3 library with your keys, then generating those signed URLs to pass back at the clients request. Hope that helps.