whenOrNull<TResult extends Object?> method

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>(TResult? $default(String title, @JsonKey.new(name: 'title_long') String? titleLong, String isbn, String isbn13, @JsonKey.new(name: 'dewey_decimal') String? deweyDecimal, String? binding, String? publisher, String? language, @JsonKey.new(name: 'date_published') DateTime? datePublished, String? edition, int? pages, String? dimensions, String? overview, String? image, double? msrp, String? excerpt, String? synopsys, @JsonKey.new(readValue: _readBookAuthors) List<String?>? authors, @JsonKey.new(readValue: _readBookSubjects) List<String>? subjects, @JsonKey.new(readValue: _readBookReviews) List<String>? reviews, List<Merchant>? prices, @JsonKey.new(readValue: _readBookRelated) List<String>? related,)?)

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 title, @JsonKey(name: 'title_long')  String? titleLong,  String isbn,  String isbn13, @_DeweyDecimalConverter()@JsonKey(name: 'dewey_decimal')  String? deweyDecimal,  String? binding,  String? publisher,  String? language, @_DateConverter()@JsonKey(name: 'date_published')  DateTime? datePublished,  String? edition,  int? pages,  String? dimensions,  String? overview,  String? image, @_MsrpConverter()  double? msrp,  String? excerpt,  String? synopsys, @JsonKey(readValue: _readBookAuthors)  List<String?>? authors, @JsonKey(readValue: _readBookSubjects)  List<String>? subjects, @JsonKey(readValue: _readBookReviews)  List<String>? reviews,  List<Merchant>? prices, @JsonKey(readValue: _readBookRelated)  List<String>? related)?  $default,) {final _that = this;
switch (_that) {
case _Book() when $default != null:
return $default(_that.title,_that.titleLong,_that.isbn,_that.isbn13,_that.deweyDecimal,_that.binding,_that.publisher,_that.language,_that.datePublished,_that.edition,_that.pages,_that.dimensions,_that.overview,_that.image,_that.msrp,_that.excerpt,_that.synopsys,_that.authors,_that.subjects,_that.reviews,_that.prices,_that.related);case _:
  return null;

}
}