Pascal (Lazarus/Delphi)

HttpPostJson2Async Example

Demonstrates use of the HttpPostJson2Async method. 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.Task,
  Chilkat.HttpResponse,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  jsonBody: string;
  task: TTask;
  resp: THttpResponse;
  statusCode: Integer;
  json: TJsonObject;

begin
  success := False;

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

  //  See PostJson2 Example for the synchronous equivalent of this example.

  http := THttp.Create;

  //  Sends a POST equivalent to the following CURL command:

  //  curl -X POST https://sandbox.plaid.com/institutions/get \
  //    -H 'content-type: application/json' \
  //    -d '{
  //      "client_id": String,
  //      "secret":String,
  //      "count": Number,
  //      "offset": Number
  //    }'

  //  Suppress some default headers that would automatically added..
  http.AcceptCharset := '';
  http.UserAgent := '';
  http.AcceptLanguage := '';
  http.AllowGzip := False;

  jsonBody := '{"client_id": "PLAID_CLIENT_ID", "secret":"PLAID_SECRET", "count": 10, "offset": 0}';
  task := http.PostJson2Async('https://sandbox.plaid.com/institutions/get','application/json',jsonBody);
  if (http.LastMethodSuccess = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  //  Start the background task.
  success := task.Run();
  if (not success) then
    begin
      WriteLn(task.LastErrorText);
      task.Free;
      Exit;
    end;

  //  The application is now free to do anything else
  //  while the HTTP POST is in progress

  //  For this example, we'll simply sleep and periodically
  //  check to see if the HTTP POST is finished.  
  while task.Finished <> True do
    begin
      //  Sleep 100 ms.
      task.SleepMs(100);
    end;

  //  When we get here, the task is either finished successfully or not, or was canceled/aborted.

  //  If the task was "canceled", it was canceled prior to actually starting.  This could
  //  happen if the task was canceled while waiting in a thread pool queue to be scheduled by Chilkat's
  //  background thread pool scheduler.  

  //  If the task was "aborted", it indicates that it was canceled while running in a background thread.  
  //  The ResultErrorText will likely indicate that the task was aborted.

  //  If the task "completed", then it ran to completion, but the actual success/failure of the method
  //  is determined by getting the result of the underlying method call.
  //  A task status of 7 indicates completion.
  if (task.StatusInt <> 7) then
    begin
      WriteLn('Task did not complete.');
      WriteLn('task status: ' + task.Status);
      task.Free;
      Exit;
    end;

  //  When called synchronously, the PostJson2 method returns an HTTP response object,
  //  unless the method failed and there was no response to be had.
  //  Check to see if PostJson2 method failed (and thus there is no response object).
  if (task.TaskSuccess = False) then
    begin
      WriteLn('The underlying task failed, and there is no HTTP response object.');
      WriteLn('The LastErrorText for the underlying method call is:');
      WriteLn(task.ResultErrorText);
      task.Free;
      Exit;
    end;

  //  To get the HTTP response object, create a new instance and load it with the result from the task.
  resp := THttpResponse.Create;
  resp.LoadTaskResult(task);
  task.Free;

  statusCode := resp.StatusCode;
  WriteLn('Response status code = ' + statusCode);

  //  Examine the JSON response..
  json := TJsonObject.Create;
  json.Load(resp.BodyStr);
  json.EmitCompact := False;
  WriteLn('JSON Response Body:');
  WriteLn(json.Emit());


  http.Free;
  resp.Free;
  json.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.