Pascal (Lazarus/Delphi)

Refresh a Dynamics CRM OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an expiring Dynamics CRM access token using the refresh token. endpoint.

(If a REST API call fails with a 401 unauthorized error, an application can auto-recover by refreshing the access token, and then re-send the request using the new token.)

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.CkDateTime,
  Chilkat.FileAccess,
  Chilkat.HttpResponse,
  Chilkat.HttpRequest,
  Chilkat.JsonObject,
  Chilkat.Http;

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

procedure RunDemo;
var
  success: Boolean;
  json: TJsonObject;
  dtExpire: TCkDateTime;
  req: THttpRequest;
  http: THttp;
  resp: THttpResponse;
  fac: TFileAccess;

begin
  success := False;

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

  //  We previously obtained an access token and saved the JSON to a file using this example:
  //  Get Dynamics CRM OAuth2 Access Token

  //  This example will examine the JSON and expiration date, and if near expiration will
  //  refresh the access token.

  json := TJsonObject.Create;
  success := json.LoadFile('qa_data/tokens/dynamicsCrm.json');
  if (success <> True) then
    begin
      Exit;
    end;

  //  The contents of the JSON look like this:
  //  {
  //    "token_type": "Bearer",
  //    "scope": "user_impersonation",
  //    "expires_in": "3599",
  //    "ext_expires_in": "0",
  //    "expires_on": "1524783438",
  //    "not_before": "1524779538",
  //    "resource": "https://mydomain.api.crm.dynamics.com",
  //    "access_token": "...",
  //    "refresh_token": "...",
  //    "id_token": "..."
  //  }

  //  The "expires_on" value is a Unix time.
  dtExpire := TCkDateTime.Create;
  dtExpire.SetFromUnixTime(False,json.IntOf('expires_on'));

  //  If this date/time expires within 10 minutes of the current system time, refresh the token.

  //  OK, we need to refresh the access token by sending a POST...
  //  

  req := THttpRequest.Create;
  req.AddParam('grant_type','refresh_token');
  req.AddParam('redirect_uri','http://localhost:3017/');
  req.AddParam('client_id','DYNAMICS-CRM-CLIENT-ID');
  req.AddParam('client_secret','DYNAMICS-CRM-SECRET-KEY');
  req.AddParam('refresh_token',json.StringOf('refresh_token'));
  req.AddParam('resource','https://mydynamicsdomain.api.crm.dynamics.com');

  http := THttp.Create;

  req.HttpVerb := 'POST';
  req.ContentType := 'application/x-www-form-urlencoded';

  resp := THttpResponse.Create;
  success := http.HttpReq('https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token',req,resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  //  Load the JSON response.
  json.Load(resp.BodyStr);
  json.EmitCompact := False;

  //  Show the JSON response.
  WriteLn(json.Emit());

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

  //  If the response status code is not 200, then it's an error.
  if (resp.StatusCode <> 200) then
    begin
      Exit;
    end;

  //  If an "expires_on" member does not exist, then add the JSON member by
  //  getting the current system date/time and adding the "expires_in" seconds.
  //  This way we'll know when the token expires.
  if (json.HasMember('expires_on') <> True) then
    begin
      dtExpire.SetFromCurrentSystemTime();
      dtExpire.AddSeconds(json.IntOf('expires_in'));
      json.AppendString('expires_on',dtExpire.GetAsUnixTimeStr(False));
    end;

  //  Save the refreshed access token JSON to a file for future requests.
  fac := TFileAccess.Create;
  fac.WriteEntireTextFile('qa_data/tokens/dynamicsCrm.json',json.Emit(),'utf-8',False);


  json.Free;
  dtExpire.Free;
  req.Free;
  http.Free;
  resp.Free;
  fac.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.