Pascal (Lazarus/Delphi)

Get the Last-Modified Date Before HTTP Download

See more HTTP Examples

Demonstrates how to send a HEAD request to get the last-modified date of a file on a web server (without downloading the file). Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Http,
  Chilkat.DtObj,
  Chilkat.HttpResponse,
  Chilkat.CkDateTime;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  resp: THttpResponse;
  lastModStr: string;
  ckdt: TCkDateTime;
  dt: TDtObj;

begin
  success := False;

  //  This example assumes the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  http := THttp.Create;

  resp := THttpResponse.Create;
  success := http.HttpNoBody('HEAD','https://www.chilkatsoft.com/hamlet.xml',resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  //  Examine the response header.
  WriteLn(resp.Header);

  //  Here is a sample response header:

  //  	Content-Length: 279658
  //  	Content-Type: text/xml
  //  	Last-Modified: Thu, 12 May 2016 15:14:08 GMT
  //  	Accept-Ranges: bytes
  //  	ETag: "c1cd8bee60acd11:0"
  //  	Server: Microsoft-IIS/8.5
  //  	X-Powered-By: ASP.NET
  //  	X-Powered-By-Plesk: PleskWin
  //  	Date: Thu, 25 Jul 2019 16:40:54 GMT

  //  Get the Last-Modified header.
  lastModStr := resp.GetHeaderField('Last-Modified');
  //  If the header exists...
  if (resp.LastMethodSuccess = True) then
    begin
      //  Parse the RFC822 format date/time string
      ckdt := TCkDateTime.Create;
      ckdt.SetFromRfc822(lastModStr);

      //  If we want to access individual date/time parts (in the local timezone)
      dt := TDtObj.Create;
      ckdt.ToDtObj(True,dt);

      WriteLn('day/month/year = ' + dt.Day + '/' + dt.Month + '/' + dt.Year);
    end;


  http.Free;
  resp.Free;
      ckdt.Free;
      dt.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.