`unstable_createFileUploadHandler`

A Node.js upload handler that will write parts with a filename to disk to keep them out of memory, parts without a filename will not be parsed. Should be composed with another upload handler.

Example:

export const action = async ({ request }: ActionArgs) => {
  const uploadHandler = unstable_composeUploadHandlers(
    unstable_createFileUploadHandler({
      maxPartSize: 5_000_000,
      file: ({ filename }) => filename,
    }),
    // parse everything else into memory
    unstable_createMemoryUploadHandler()
  );
  const formData = await unstable_parseMultipartFormData(
    request,
    uploadHandler
  );

  const file = formData.get("avatar");

  // file is a "NodeOnDiskFile" which implements the "File" API
  // ... etc
};

Options:

Property	Type	Default	Description
avoidFileConflicts	boolean	true	Avoid file conflicts by appending a timestamp on the end of the filename if it already exists on disk
directory	string \| Function	os.tmpdir()	The directory to write the upload.
file	Function	() => `upload_${random}.${ext}`	The name of the file in the directory. Can be a relative path, the directory structure will be created if it does not exist.
maxPartSize	number	3000000	The maximum upload size allowed (in bytes). If the size is exceeded a MaxPartSizeExceededError will be thrown.
filter	Function	OPTIONAL	A function you can write to prevent a file upload from being saved based on filename, content type, or field name. Return `false` and the file will be ignored.

The function API for file and directory are the same. They accept an object and return a string. The object it accepts has filename, name, and contentType (all strings). The string returned is the path.

The filter function accepts an object and returns a boolean (or a promise that resolves to a boolean). The object it accepts has the filename, name, and contentType (all strings). The boolean returned is true if you want to handle that file stream.