Modifying FormData body in beforeRequest hook does not work

[stevensacks]

I wanted to snake case my FormData beforeRequest. The ky-hooks-change-case library only works with non-FormData. So, I wrote my own.

export const snakeCaseBody = (original) => {
  if (original instanceof FormData) {
    const body = new FormData();

    [...original.keys()].forEach((key) => {
      body.set(snakeCase(key), original.get(key)!);
    });

    return body;
  }

  return JSON.stringify(toSnakeCase(JSON.parse(original)));
};

export const requestToSnakeCase = async (request, options) => {
  if (options.body) {
    const body = snakeCaseBody(options.body);

    return new Request(request, {body});
  }
};

I've got a unit test that proves snakeCaseBody works. I also logged the Content-Type header of the request and it looks correct:

Content-Type multipart/form-data; boundary=----formdata-undici-066001922265

But on the receiving end of the API, I get an error that the body cannot be parsed as FormData.

Is this a limitation in ky, or am I doing something wrong?

[sholladay]

As long as the boundary is correct, I would expect it to work. We've had problems with that before.

[stevensacks]

Ok thanks. I’ll keep experimenting and see if I can figure it out.