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ContentLength

property ContentLength: Integer read write;

Example​

procedure ScriptEvent(var Value: variant);
begin
  if Response <> nil then
  begin
    Response.ContentString := 'ready';
    Value := Response.ContentLength; { provisional character count: 5 }
  end;
end;

Usage​

ContentLength exposes a provisional script-Integer content length that automatic sending discards and recalculates from encoded text or stream size.

Additional Technical Info​

The native WebBroker/Indy property is Int64; Velox exposes it through a PascalScript Integer helper. A write accepts only the script integer range. A read narrows the current native value and can raise ERangeError when a stream or native producer has established a size outside that range.

During script execution the value is provisional:

  • assigning ContentString sets it to the Unicode string's character count, not its encoded byte count;
  • assigning Content sets it to the stream's native Size; and
  • a script can assign another integer, including negative values.

Immediately before the normal response is sent, TIdHTTPAppResponse.SendResponse unconditionally resets the native value to -1. Indy then calculates the actual field from the encoded text byte count or stream Size, or uses zero for HEAD/1xx/204/304. Consequently a script assignment does not constrain or truncate automatic response output and should not be used as a size-enforcement mechanism.

Indy gives nonempty text priority over the stream when calculating and writing. If neither body source is present for an ordinary response, it generates a small HTML status body and calculates that length. If a transfer coding is configured, HTTP framing rules can omit/ignore Content-Length.

Do not add a separate Content-Length custom header: duplicate or conflicting framing is unsafe. Bound the data before storing it, choose one body source, and let automatic sending calculate the field. Reading this property does not measure the final encoded wire length. Test Response for nil.

External references

Created 2026-07-15