Delphi DLL

HttpPostJson2Async Example

Demonstrates use of the HttpPostJson2Async method. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, Task, HttpResponse, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
http: HCkHttp;
jsonBody: PWideChar;
task: HCkTask;
resp: HCkHttpResponse;
statusCode: Integer;
json: HCkJsonObject;

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 := CkHttp_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..
CkHttp_putAcceptCharset(http,'');
CkHttp_putUserAgent(http,'');
CkHttp_putAcceptLanguage(http,'');
CkHttp_putAllowGzip(http,False);

jsonBody := '{"client_id": "PLAID_CLIENT_ID", "secret":"PLAID_SECRET", "count": 10, "offset": 0}';
task := CkHttp_PostJson2Async(http,'https://sandbox.plaid.com/institutions/get','application/json',jsonBody);
if (CkHttp_getLastMethodSuccess(http) = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

// Start the background task.
success := CkTask_Run(task);
if (not success) then
  begin
    Memo1.Lines.Add(CkTask__lastErrorText(task));
    CkTask_Dispose(task);
    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 CkTask_getFinished(task) <> True do
  begin
    // Sleep 100 ms.
    CkTask_SleepMs(task,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 (CkTask_getStatusInt(task) <> 7) then
  begin
    Memo1.Lines.Add('Task did not complete.');
    Memo1.Lines.Add('task status: ' + CkTask__status(task));
    CkTask_Dispose(task);
    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 (CkTask_getTaskSuccess(task) = False) then
  begin
    Memo1.Lines.Add('The underlying task failed, and there is no HTTP response object.');
    Memo1.Lines.Add('The LastErrorText for the underlying method call is:');
    Memo1.Lines.Add(CkTask__resultErrorText(task));
    CkTask_Dispose(task);
    Exit;
  end;

// To get the HTTP response object, create a new instance and load it with the result from the task.
resp := CkHttpResponse_Create();
CkHttpResponse_LoadTaskResult(resp,task);
CkTask_Dispose(task);

statusCode := CkHttpResponse_getStatusCode(resp);
Memo1.Lines.Add('Response status code = ' + IntToStr(statusCode));

// Examine the JSON response..
json := CkJsonObject_Create();
CkJsonObject_Load(json,CkHttpResponse__bodyStr(resp));
CkJsonObject_putEmitCompact(json,False);
Memo1.Lines.Add('JSON Response Body:');
Memo1.Lines.Add(CkJsonObject__emit(json));

CkHttp_Dispose(http);
CkHttpResponse_Dispose(resp);
CkJsonObject_Dispose(json);

end;