whenOrNull<TResult extends Object?> method

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? $default(int total, @JsonKey.new(readValue: _readBookQueryBooks) List<Book> books, @JsonKey.new(includeIfNull: false) int? page, @JsonKey.new(name: 'page_size', includeIfNull: false) int? pageSize,)?)

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( int total, @JsonKey(readValue: _readBookQueryBooks)  List<Book> books, @JsonKey(includeIfNull: false)  int? page, @JsonKey(name: 'page_size', includeIfNull: false)  int? pageSize)?  $default,) {final _that = this;
switch (_that) {
case _BookQueryResult() when $default != null:
return $default(_that.total,_that.books,_that.page,_that.pageSize);case _:
  return null;

}
}