A hook for uploading files using multipart form data with React Native. Provides a simple way to track upload progress, abort an upload, and handle timeouts. Written in TypeScript and no dependencies required.

yarn add react-native-use-file-upload

There is an example app in this repo as shown in the above gif. It is located within example and there is a small node server script within example/server here. You can start the node server within example using yarn server.

import useFileUpload, { UploadItem } from 'react-native-use-file-upload';

// Used in optional type parameter for useFileUpload
interface Item extends UploadItem {
  progress?: number;
}

// ...
const [data, setData] = useState<Item[]>([]);
// The generic type param below for useFileUpload is optional
// and defaults to UploadItem. It should inherit UploadItem.
const { startUpload, abortUpload } = useFileUpload<Item>({
  url: 'https://example.com/upload',
  field: 'file',
  // Below options are optional
  method: 'POST',
  data,
  headers,
  timeout: 60 * 1000, // 60 seconds
  onProgress,
  onDone,
  onError,
  onTimeout,
});

const onPressUpload = async () => {
  const promises = data.map((item) => startUpload(item));
  // Use Promise.all instead if you want to throw an error from a timeout or error.
  // As of October 2022 you have to polyfill allSettled in React Native.
  const result = await Promise.allSettled(promises);
};

Start a file upload for a given file. Returns a promise that resolves with OnDoneData or rejects with OnErrorData.

// Objects passed to startUpload should have the below shape at least (UploadItem type)
startUpload({
  name: 'file.jpg',
  type: 'image/jpg',
  uri: 'file://some-local-file.jpg',
});

Abort a file upload for a given file. The promise from startUpload gets rejected and onError runs if present.

// Pass the uri of a file that started uploading
abortUpload('file://some-local-file.jpg');

const headers = new Headers();
headers.append('Authorization', 'foo');
useFileUpload({ headers });

// OnProgressData type
{
  item: UploadItem; // or a type that inherits UploadItem
  event: ProgressEvent;
};
// event is the XMLHttpRequest progress event object and it's shape is -
{
  loaded: number,
  total: number
}

// OnDoneData type
{
  item: UploadItem; // or a type that inherits UploadItem
  responseBody: string; // eg "{\"foo\":\"baz\"}" (JSON) or "foo"
  responseHeaders: string;
}

// onErrorData type
{
  item: UploadItem; // or a type that inherits UploadItem
  error: string;
}

// OnErrorData type
{
  item: UploadItem; // or a type that inherits UploadItem
  error: string;
  timeout: boolean; // true here
}

Requests continue when the app is backgrounded on android but they do not on iOS. This can be addressed by using react-native-background-upload.

The React Native team did a heavy lift to polyfill and bridge XMLHttpRequest to the native side for us. There is an open PR in React Native to allow network requests to run in the background for iOS. react-native-background-upload is great but if backgrounding can be supported without any external native dependencies it is a win for everyone.

You can throttle the file uploads by using ngrok and Network Link Conditioner. Once you have ngrok installed you can start a HTTP tunnel forwarding to the local node server on port 8080 via:

ngrok http 8080

ngrok will generate a forwarding URL to the local node server and you should set this as the url for useFileUpload. This will make your device/simulator make the requests against the ngrok forwarding URL.

You can throttle your connection using Network Link Conditioner if needed. The existing Wifi profile with a 33 Mbps upload works well and you can add a custom profile also. If your upload speed is faster than 100 Mbps you'll see a difference by throttling with Network Link Conditioner. You might not need to throttle with Network Link Conditioner depending on your connection upload speed.

It is possible to to send multiple files in 1 request. There are downsides to this approach though and the main one is that it is slower. A client has the ability to handle multiple server connections simultaneously, allowing the files to stream in parallel. This folds the upload time over on itself.

Another downside is fault tolerance. By splitting the files into separate requests, this strategy allows for a file upload to fail in isolation. If the connection fails for the request, or the file is invalidated by the server, or any other reason, that file upload will fail by itself and won't affect any of the other uploads.

This is because of how React Native abstracts away setting the content-disposition request header for us in their polyfill for FormData. You can see here how that is being done in the getParts function.

MIT

Made with create-react-native-library