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OptBoolean

function OptBoolean(const aName: String;
  const aDefault: Boolean): Boolean;

Example​

procedure ScriptEvent(var Value: variant);
var
  Payload: TJSONObject;
begin
  Payload := TJSONObject.CreateFromString('{"enabled":true}');
  try
    Value := Payload.OptBoolean('enabled', False);
  finally
    Payload.Free;
  end;
end;

Usage​

OptBoolean returns the required default for a missing or null field and otherwise applies Velox's permissive true-only Boolean conversion.

Additional Technical Info​

OptBoolean performs a side-effect-free, case-insensitive FindValue lookup. The PascalScript declaration requires aDefault, which is returned only when the first matching field is absent or its node is null.

A native TJSONBoolean returns its stored value. Every other non-null node is converted by comparing AsString case-insensitively with true. Therefore 'true' returns True, while 'false', 'yes', '1', any number and structured text return False rather than the supplied default.

The method does not create a missing null field. Duplicate names select the first physical occurrence. To distinguish an explicit invalid representation from false, inspect the node and ValueType with FindValue before conversion.

External references

Created 2026-07-20