Function formDataToStream

lib/helpers/formDataToStream.js:68–117

(form, headersHandler, options)

}

const formDataToStream = (form, headersHandler, options) => {
  const {
    tag = 'form-data-boundary',
    size = 25,
    boundary = tag + '-' + platform.generateString(size, BOUNDARY_ALPHABET),
  } = options || {};

  if (!utils.isFormData(form)) {
    throw new TypeError('FormData instance required');
  }

  if (boundary.length < 1 || boundary.length > 70) {
    throw new Error('boundary must be 1-70 characters long');
  }

  const boundaryBytes = textEncoder.encode('--' + boundary + CRLF);
  const footerBytes = textEncoder.encode('--' + boundary + '--' + CRLF);
  let contentLength = footerBytes.byteLength;

  const parts = Array.from(form.entries()).map(([name, value]) => {
    const part = new FormDataPart(name, value);
    contentLength += part.size;
    return part;
  });

  contentLength += boundaryBytes.byteLength * parts.length;

  contentLength = utils.toFiniteNumber(contentLength);

  const computedHeaders = {
    'Content-Type': `multipart/form-data; boundary=${boundary}`,
  };

  if (Number.isFinite(contentLength)) {
    computedHeaders['Content-Length'] = contentLength;
  }

  headersHandler && headersHandler(computedHeaders);

  return Readable.from(
    (async function* () {
      for (const part of parts) {
        yield boundaryBytes;
        yield* part.encode();
      }

      yield footerBytes;
    })()
  );
};

export default formDataToStream;