onRequest method

@override void onRequest(RequestOptions options, RequestInterceptorHandler handler)

Called when the request is about to be sent.

Implementation

@override
void onRequest(
  RequestOptions options,
  RequestInterceptorHandler handler,
) async {
  // Already FormData - just ensure content type
  if (options.data is FormData) {
    options.contentType ??= 'multipart/form-data';
    handler.next(options);
    return;
  }

  // Check for files in Map data
  if (options.data is Map<String, dynamic>) {
    final data = options.data as Map<String, dynamic>;

    if (_containsFiles(data)) {
      final formData = await _toFormData(data);
      options.data = formData;
      options.contentType = 'multipart/form-data';
      handler.next(options);
      return;
    }
  }

  // Apply default content type for non-null data (if not already set)
  if (options.contentType == null &&
      options.data != null &&
      defaultContentType != null) {
    options.contentType = defaultContentType;
  }

  handler.next(options);
}