Pascal (Lazarus/Delphi)

Creating an application/json HTTP POST Request

See more HTTP Examples

Demonstrates how to create an HTTP POST request having the Content-Type application/json, where the body of the HTTP request is the following JSON:

{
   "username" : "my_username",
   "password" : "my_password",
   "validation-factors" : {
      "validationFactors" : [
         {
            "name" : "remote_address",
            "value" : "127.0.0.1"
         }
      ]
   }
}

The generated HTTP request looks like this:

POST /something HTTP/1.1
Content-Type: application/json
Accept: application/json
Host: domain
Content-Length: 216

{
  "username": "my_username",
  "password": "my_password",
  "validation-factors": {
    "validationFactors": [
      {
        "name": "remote_address",
        "value": "127.0.0.1"
      }
    ]
  }
}

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.JsonArray,
  Chilkat.HttpRequest,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  req: THttpRequest;
  json: TJsonObject;
  vFactors: TJsonObject;
  vArray: TJsonArray;
  factorObj: TJsonObject;
  requestMime: string;

begin
  //  This example demonstrates building an application/json request.

  req := THttpRequest.Create;

  //  The ContentType, HttpVerb, and Path properties should
  //  always be explicitly set.
  req.HttpVerb := 'POST';
  req.Path := '/something';
  req.ContentType := 'application/json';

  //  We may wish to add an "Accept" header to the request.
  //  This tells the server we'll accept an application/json response.
  req.AddHeader('Accept','application/json');

  //  We'll use Chilkat's JSON API to create the JSON body of the HTTP request.
  json := TJsonObject.Create;
  json.AppendString('username','my_username');
  json.AppendString('password','my_password');

  vFactors := TJsonObject.Create;
  json.AppendObject2('validation-factors',vFactors);

  vArray := TJsonArray.Create;
  vFactors.AppendArray2('validationFactors',vArray);

  factorObj := TJsonObject.Create;
  vArray.AddObjectAt2(0,factorObj);
  factorObj.AppendString('name','remote_address');
  factorObj.AppendString('value','127.0.0.1');

  //  Use the JSON for the HTTP request body
  //  By default, the Emit method will output compact JSON.
  //  This is best for generating the smallest size request.
  //  To generate a more human-readable (pretty-printed) JSON request body,
  //  set the EmitCompact property to FALSE
  json.EmitCompact := False;
  req.LoadBodyFromString(json.Emit(),'utf-8');

  //  View the request that would be sent if HttpSReq was called:
  requestMime := req.GenerateRequestText();
  WriteLn(requestMime);

  //  A few important comments about the HTTP request that is generated:
  //  
  //  1) The Content-Length header is automatically generated based on the actual length of the MIME message
  //     that follows the intial (topmost) MIME header.
  //  2) The HOST header will automatically get filled in with the actual domain when HttpSReq
  //     is called.


  req.Free;
  json.Free;
  vFactors.Free;
  vArray.Free;
  factorObj.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.