Pascal (Lazarus/Delphi)

curl POST with JSON Input and JSON Output

See more CURL Examples

Demonstrates running a simple curl command with JSON input and JSON output. 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.StringBuilder,
  Chilkat.HttpCurl,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  sbTargetCurl: TStringBuilder;
  httpCurl: THttpCurl;
  responseJson: TJsonObject;
  statusCode: Integer;
  targetCurl: string;

begin
  success := False;

  //  Run the following curl command

  //   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;

  //  Run the curl command.
  success := httpCurl.DoYourThing(sbTargetCurl.GetAsString());
  if (success = False) then
    begin
      WriteLn(httpCurl.LastErrorText);
      Exit;
    end;

  responseJson := TJsonObject.Create;
  responseJson.EmitCompact := False;

  httpCurl.GetResponseJson(responseJson);

  statusCode := httpCurl.StatusCode;
  WriteLn('response status code: ' + statusCode);

  WriteLn(responseJson.Emit());

  //  Output:

  //  response status code: 200
  //  {
  //    "args": {},
  //    "data": "{\r\n            \"title\": \"foo\",\r\n            \"body\": \"bar\",\r\n            \"userId\": 1\r\n          }",
  //    "files": {},
  //    "form": {},
  //    "headers": {
  //      "Content-Length": "96",
  //      "Content-Type": "application/json",
  //      "Host": "httpbin.org",
  //      "X-Amzn-Trace-Id": "Root=1-69e8db8b-459b3bdf7b7a3bc749184968"
  //    },
  //    "json": {
  //      "body": "bar",
  //      "title": "foo",
  //      "userId": 1
  //    },
  //    "origin": "123.222.222.222",
  //    "url": "https://httpbin.org/post"
  //  }

  //  ----------------------------------------------------------------------------------
  //  Another example:

  //  curl -X POST https://postman-echo.com/post \
  //       -H "Content-Type: application/json" \
  //       -d '{"foo":"bar"}'

  targetCurl := 'curl -X POST https://postman-echo.com/post -H "Content-Type: application/json" -d ''{"foo":"bar"}''';

  //  Run the curl command.
  success := httpCurl.DoYourThing(targetCurl);
  if (success = False) then
    begin
      WriteLn(httpCurl.LastErrorText);
      Exit;
    end;

  httpCurl.GetResponseJson(responseJson);

  statusCode := httpCurl.StatusCode;
  WriteLn('response status code: ' + statusCode);

  WriteLn(responseJson.Emit());

  //  Output:

  //  response status code: 200
  //  {
  //    "args": {},
  //    "data": {
  //      "foo": "bar"
  //    },
  //    "files": {},
  //    "form": {},
  //    "headers": {
  //      "host": "postman-echo.com",
  //      "content-length": "13",
  //      "content-type": "application/json",
  //      "x-forwarded-proto": "https",
  //      "accept-encoding": "gzip, br"
  //    },
  //    "json": {
  //      "foo": "bar"
  //    },
  //    "url": "https://postman-echo.com/post"
  //  }


  sbTargetCurl.Free;
  httpCurl.Free;
  responseJson.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.