whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>({
  1. TResult? openUrl(
    1. String url,
    2. String label,
    3. @JsonKey.new(name: 'open_in_app') bool openInApp,
    4. String style,
    )?,
  2. TResult? sendMessage(
    1. String url,
    2. String label,
    3. @JsonKey.new(name: 'open_in_app') bool openInApp,
    4. String style,
    )?,
  3. TResult? callback(
    1. @JsonKey.new(name: 'callback_id') String callbackId,
    2. String label,
    3. Map<String, dynamic>? payload,
    4. String style,
    )?,
  4. TResult? requestInput(
    1. @JsonKey.new(name: 'input_type') String inputType,
    2. String label,
    3. String source,
    4. String style,
    )?,
  5. TResult? changeLanguage(
    1. String locale
    )?,
})

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( String url,  String label, @JsonKey(name: 'open_in_app')  bool openInApp,  String style)?  openUrl,TResult? Function( String message,  String label, @JsonKey(name: 'show_in_chat')  bool showInChat,  String style)?  sendMessage,TResult? Function(@JsonKey(name: 'callback_id')  String callbackId,  String label,  Map<String, dynamic>? payload,  String style)?  callback,TResult? Function(@JsonKey(name: 'input_type')  String inputType,  String label,  String source,  String style)?  requestInput,TResult? Function( String locale)?  changeLanguage,}) {final _that = this;
switch (_that) {
case OpenUrlAction() when openUrl != null:
return openUrl(_that.url,_that.label,_that.openInApp,_that.style);case SendMessageAction() when sendMessage != null:
return sendMessage(_that.message,_that.label,_that.showInChat,_that.style);case CallbackAction() when callback != null:
return callback(_that.callbackId,_that.label,_that.payload,_that.style);case RequestInputAction() when requestInput != null:
return requestInput(_that.inputType,_that.label,_that.source,_that.style);case ChangeLanguageAction() when changeLanguage != null:
return changeLanguage(_that.locale);case _:
  return null;

}
}