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TJSONBoolean

TJSONBoolean = class(TJSONValue)

Example​

procedure ScriptEvent(var Value: variant);
var
  Flag: TJSONBoolean;
begin
  Flag := TJSONBoolean.Create;
  try
    Flag.Value := True;
    Value := Flag.AsString;  // true
  finally
    Flag.Free;
  end;
end;

Usage​

TJSONBoolean represents a mutable JSON Boolean node with exact lowercase literals and separate retained payload and null state.

Additional Technical Info​

TJSONBoolean stores one native Boolean as a JSON scalar. The inherited virtual Create constructor is available on this class and produces a non-null node whose initial Value is False. A directly created node belongs to the script and must be freed; a node returned from an object or array is normally borrowed and owned by that parent.

The class-specific generated surface is only Value. Shared construction, cloning, conversion, name and null-state members are documented under TJSONValue. ValueType remains jsBoolean even when the separate IsNull flag is true.

When non-null, AsString is exactly the lowercase JSON literal true or false. AsBoolean returns the stored value, while integer conversions return 1 or 0. Setting inherited AsString accepts only an exact case-insensitive true or false; surrounding whitespace is not trimmed. An invalid text assignment clears the null flag before raising and leaves the previous Boolean payload in place.

Clear marks the node null without erasing its stored Boolean. Reading Value still exposes that retained payload, whereas AsString becomes blank and AsBoolean becomes False. Assigning Value makes the node non-null again.

Serialization and null behavior​

Objects emit a null-marked Boolean as null. Arrays have a traced defect: their serializer branches on ValueType, receives blank AsString for a null-marked Boolean and emits an empty token. A one-item array therefore collapses to [], while mixed arrays can become invalid JSON. Use a real TJSONNull node when an array must contain JSON null.

The PascalScript runtime also misbinds inherited NotNull to the IsNull read helper, so the two script properties return the same value. Test IsNull directly and invert it when a non-null predicate is required.

Inherited CopyFrom must receive another TJSONBoolean; the override performs no runtime type check. IsEqual compares type, case-sensitive name and AsString, not the null flag, so two cleared Boolean nodes with different retained payloads can compare equal.

External references

Created 2026-07-20