whenOrNull<TResult extends Object?> method

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? $default(bool showErrorMsg, String loadingText, String? contentType, Map<String, dynamic> headers, bool showDefaultLoading, dynamic data, ResponseType? responseType, bool? nullParams, RequestEncoder? requestEncoder, DioStart? dioStart, bool? returnIsString, String? fullUrl, InterceptorCall? interceptorCall, UrlParseFormat? urlParseFormat, ResponseResultCallback? responseResultCallback, Map<String, dynamic>? extra, CancelToken? cancelToken, ProgressCallback? onSendCallback, ProgressCallback? onReceiveProgress, String? downloadUrl, File? savePath,)?)

A variant of when that fallback to returning null

It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}

Implementation

@optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>(
  TResult? Function(
          bool showErrorMsg,
          String loadingText,
          String? contentType,
          Map<String, dynamic> headers,
          bool showDefaultLoading,
          @JsonKey(name: 'data', toJson: _dataToJson) dynamic data,
          ResponseType? responseType,
          bool? nullParams,
          @igFreezedJson RequestEncoder? requestEncoder,
          @igFreezedJson DioStart? dioStart,
          bool? returnIsString,
          @igFreezedJson String? fullUrl,
          @igFreezedJson InterceptorCall? interceptorCall,
          @igFreezedJson UrlParseFormat? urlParseFormat,
          @igFreezedJson ResponseResultCallback? responseResultCallback,
          Map<String, dynamic>? extra,
          @igFreezedJson CancelToken? cancelToken,
          @igFreezedJson ProgressCallback? onSendCallback,
          @igFreezedJson ProgressCallback? onReceiveProgress,
          String? downloadUrl,
          @igFreezedJson File? savePath)?
      $default,
) {
  final _that = this;
  switch (_that) {
    case _RequestParams() when $default != null:
      return $default(
          _that.showErrorMsg,
          _that.loadingText,
          _that.contentType,
          _that.headers,
          _that.showDefaultLoading,
          _that.data,
          _that.responseType,
          _that.nullParams,
          _that.requestEncoder,
          _that.dioStart,
          _that.returnIsString,
          _that.fullUrl,
          _that.interceptorCall,
          _that.urlParseFormat,
          _that.responseResultCallback,
          _that.extra,
          _that.cancelToken,
          _that.onSendCallback,
          _that.onReceiveProgress,
          _that.downloadUrl,
          _that.savePath);
    case _:
      return null;
  }
}