whenOrNull<TResult extends Object?> method

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({ TResult? user(String id, String chatId, String userId, DateTime timestamp, String text,)?, TResult? assistant(String id, String chatId, String userId, DateTime timestamp, String? modelId, String text,)?, TResult? context(String id, String chatId, String userId, DateTime timestamp, String text,)?, TResult? historySummary(String id, String chatId, String userId, DateTime timestampFrom, DateTime timestamp, String? modelId, String text,)?, })

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 id,  String chatId,  String userId,  DateTime timestamp,  String text)?  user,TResult? Function( String id,  String chatId,  String userId,  DateTime timestamp,  String? modelId,  String text)?  assistant,TResult? Function( String id,  String chatId,  String userId,  DateTime timestamp,  String text)?  context,TResult? Function( String id,  String chatId,  String userId,  DateTime timestampFrom,  DateTime timestamp,  String? modelId,  String text)?  historySummary,}) {final _that = this;
switch (_that) {
case UserItem() when user != null:
return user(_that.id,_that.chatId,_that.userId,_that.timestamp,_that.text);case AssistantItem() when assistant != null:
return assistant(_that.id,_that.chatId,_that.userId,_that.timestamp,_that.modelId,_that.text);case ContextItem() when context != null:
return context(_that.id,_that.chatId,_that.userId,_that.timestamp,_that.text);case HistorySummaryItem() when historySummary != null:
return historySummary(_that.id,_that.chatId,_that.userId,_that.timestampFrom,_that.timestamp,_that.modelId,_that.text);case _:
  return null;

}
}