Skip to main content

HeaderByIndex

property HeaderByIndex[const aIndex: Integer]: String read;

Example​

procedure ScriptEvent(var Value: variant);
var
  I: Integer;
  Lines: string;
begin
  Http.Get('https://api.example.invalid/v1/status');
  Lines := '';
  for I := 0 to Http.Response.HeaderCount - 1 do
    Lines := Lines + Http.Response.HeaderByIndex[I] + #13#10;
  Value := Lines;
end;

Usage​

HeaderByIndex returns one zero-based physical raw response-header line including its field name and colon.

Additional Technical Info​

HeaderByIndex[index] returns the exact string stored at the zero-based position in Indy's response RawHeaders list. A normal entry includes the field name, colon and value. The list can also contain physical continuation lines and fields appended from chunked trailers.

Valid indexes are 0 through HeaderCount - 1. A negative index or an index at or above the count raises a Delphi string-list range exception; the accessor does not return an empty sentinel. Re-read HeaderCount for the same response before iterating and do not retain indexes across requests.

Unlike Header, this property preserves repeated field occurrences and physical ordering. Use it when raw diagnostic fidelity matters. Use HeaderName to parse the name at the same position. HeaderValue is not the exact indexed counterpart for duplicates because it performs a second name-based first-value lookup.

Do not emit all returned lines to ordinary logs without redaction. Raw response fields can contain authentication challenges, cookies, correlation identifiers, personal data and attacker-controlled control content. The complete list can also remain stale after a pre-terminal setup failure.

External references

Created 2026-07-20