Pascal (Lazarus/Delphi)

Viewing the Raw HTTP Request Generated from a curl Command

See more CURL Examples

This example demonstrates how to convert a curl command into the exact raw HTTP request that would be sent to the server—without actually sending it.

By calling ToRawRequest, the curl command is translated into its underlying HTTP representation, including the request line, headers, and body. This is especially useful for debugging, verifying request formatting, and understanding how a curl command maps to a real HTTP request.

In this example, a POST request with a JSON body is constructed using curl syntax. The code then converts it to the raw HTTP request format and prints the result. This allows you to inspect details such as the Content-Length, header formatting, and the exact payload being transmitted.

This technique is helpful when troubleshooting issues related to request composition, encoding, or server-side behavior.

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.HttpCurl,
  Chilkat.StringBuilder;

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

procedure RunDemo;
var
  success: Boolean;
  sbTargetCurl: TStringBuilder;
  httpCurl: THttpCurl;
  sbRawRequest: TStringBuilder;

begin
  success := False;

  //  Build a curl command and convert it to the raw HTTP request that would be sent.
  //  This allows you to inspect the exact request (headers + body) without actually sending it.

  //   curl -X POST https://httpbin.org/post \
  //        -H "Content-Type: application/json" \
  //        -d '{
  //              "title": "foo",
  //              "body": "bar",
  //              "userId": 1
  //            }'

  //  The backslashes at the end of lines are not required.  Chilkat ignores them if present.
  sbTargetCurl := TStringBuilder.Create;
  sbTargetCurl.AppendLn(' curl -X POST https://httpbin.org/post \");
  sbTargetCurl.AppendLn('      -H "Content-Type: application/json" \");
  sbTargetCurl.AppendLn('      -d ''{');
  sbTargetCurl.AppendLn('            "title": "foo",');
  sbTargetCurl.AppendLn('            "body": "bar",');
  sbTargetCurl.AppendLn('            "userId": 1');
  sbTargetCurl.AppendLn('          }''');

  httpCurl := THttpCurl.Create;

  //  Convert the curl command into a raw HTTP request string.
  //  This is useful for debugging, as it shows exactly what would be sent to the server
  //  (request line, headers, and body) for the given curl command.
  sbRawRequest := TStringBuilder.Create;
  success := httpCurl.ToRawRequest(sbTargetCurl.GetAsString(),sbRawRequest);
  if (success = False) then
    begin
      WriteLn(httpCurl.LastErrorText);
      Exit;
    end;

  //  Display the generated raw HTTP request.
  WriteLn(sbRawRequest.GetAsString());

  //  Expected output:

  //  POST /post HTTP/1.1
  //  Host: httpbin.org
  //  Content-Type: application/json
  //  Content-Length: 96
  //  
  //  {
  //              "title": "foo",
  //              "body": "bar",
  //              "userId": 1
  //            }


  sbTargetCurl.Free;
  httpCurl.Free;
  sbRawRequest.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.