whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>({
  1. TResult? messageView(
    1. MessageView data
    )?,
  2. TResult? deletedMessageView(
    1. DeletedMessageView data
    )?,
  3. TResult? messageBeforeUserJoinedGroupView(
    1. MessageBeforeUserJoinedGroupView data
    )?,
  4. TResult? unknown(
    1. Map<String, dynamic> data
    )?,
})

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( MessageView data)?  messageView,TResult? Function( DeletedMessageView data)?  deletedMessageView,TResult? Function( MessageBeforeUserJoinedGroupView data)?  messageBeforeUserJoinedGroupView,TResult? Function( Map<String, dynamic> data)?  unknown,}) {final _that = this;
switch (_that) {
case UMessageViewReplyToMessageView() when messageView != null:
return messageView(_that.data);case UMessageViewReplyToDeletedMessageView() when deletedMessageView != null:
return deletedMessageView(_that.data);case UMessageViewReplyToMessageBeforeUserJoinedGroupView() when messageBeforeUserJoinedGroupView != null:
return messageBeforeUserJoinedGroupView(_that.data);case UMessageViewReplyToUnknown() when unknown != null:
return unknown(_that.data);case _:
  return null;

}
}