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jsString

jsString = 0

Example​

function ReadJSONString(Value: TJSONValue; var Text: String): Boolean;
begin
  Result := (Value.ValueType = jsString) and Value.NotNull;
  if Result then
    Text := Value.AsString;
end;

Usage​

jsString identifies a Velox JSON string, including its mutable null state and incomplete Unicode/control-character escaping.

Additional Technical Info​

jsString is ordinal 0 of TJSONValueType and identifies a concrete TJSONString. AsString returns its decoded stored text when not null; empty string and null-marked string are distinct only when IsNull/NotNull is checked.

The reader decodes \", \\, \/, \b, \t, \n, \f and \r. Its \u branch is an unimplemented TODO: it does not decode the marker or following four hexadecimal digits as a Unicode code unit. For example, a JSON escape representing A is stored as the five text characters u0041, not A. Prefer literal Unicode input supported by the surrounding stream encoding or a standards-compliant parser when escaped Unicode is possible.

Serialization escapes quote, backslash and the five common control escapes. It deliberately leaves / unescaped, which is valid JSON, but it also leaves other control characters below U+0020 unescaped, producing invalid JSON. Object property names have a separate defect and are not passed through this escaping routine at all.

Scalar null state does not change ValueType. Clear marks a string null without erasing its stored text; setting IsNull := False can reveal that old text. While null, AsString returns empty. Assigning AsString/Value makes it non-null.

Several generic accessors parse strings as Boolean, number, date/time, GUID or enum. These conversions can be permissive, locale-sensitive or raise; check the expected kind and validate the text rather than using them as JSON schema validation.

The example is source-reviewed only; no JSON parsing, Unicode, escaping, conversion, runtime or image test ran.

Related Code Library entries

External references

Created 2026-07-15