NotNull

property NotNull: Boolean read;

Example

procedure ScriptEvent(var Value: variant);
var
  Text: TJSONString;
  Item: TJSONValue;
begin
  Text := TJSONString.Create;
  try
    Item := Text;
    Item.AsString := 'ready';
    Value := not Item.IsNull;  // Use this; do not use Item.NotNull.
  finally
    Text.Free;
  end;
end;

Usage

Do not use NotNull as a non-null test in current Velox scripts. It returns exactly the same Boolean as IsNull, rather than the inverse.

Use not Item.IsNull when a script needs to confirm that a JSON value is present. This defect is silent: the property compiles and returns the wrong meaning without warning.

Additional Technical Info

Do not use this property in Velox scripts. The native Deltics getter correctly returns the inverse of the stored null flag, and native container/null descendants override it appropriately. The PascalScript runtime importer nevertheless registers the NotNull name with TJSONValueIsNull_R instead of the existing TJSONValueNotNull_R helper.

As a result, script NotNull returns exactly the same value as IsNull for every correctly registered descendant:

Actual state/class	Script IsNull	Script NotNull
Non-null scalar	False	False
Null-marked scalar	True	True
TJSONObject / TJSONArray	False	False
TJSONNull	True	True

The compiler accepts the property and no exception warns about the misbinding, making it especially dangerous in conditions. Always write not Item.IsNull. This is a deterministic registration defect, not three-state null logic and not dependent on the payload.

Reading is constant-time and has no side effect. The result remains invalid as a non-null predicate until the runtime importer is corrected; documentation cannot repair existing compiled behavior.

Created 2026-07-15