Delphi DLL

Refresh HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an HMRC access token. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, OAuth2, StringBuilder, JsonObject, CkDateTime;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
jsonToken: HCkJsonObject;
oauth2: HCkOAuth2;
dtExpire: HCkDateTime;
sbJson: HCkStringBuilder;

begin
success := False;

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

// See Get HMRC Access Token 
// for sample code showing how to obtain a HMRC access token for desktop apps.

// It is assumed we previously obtained an OAuth2 access token for HMRC.

jsonToken := CkJsonObject_Create();
success := CkJsonObject_LoadFile(jsonToken,'qa_data/tokens/hmrc.json');
if (success <> True) then
  begin
    Memo1.Lines.Add('Failed to load hmrc.json');
    Exit;
  end;

// The access token JSON looks something 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": "..."
// }

oauth2 := CkOAuth2_Create();

CkOAuth2_putTokenEndpoint(oauth2,'https://test-api.service.hmrc.gov.uk/oauth/token');

// Replace these with actual values.
CkOAuth2_putClientId(oauth2,'HMRC-CLIENT-ID');
CkOAuth2_putClientSecret(oauth2,'HMRC-CLIENT-SECRET');

// Get the "refresh_token"
CkOAuth2_putRefreshToken(oauth2,CkJsonObject__stringOf(jsonToken,'refresh_token'));

// Send the HTTP POST to refresh the access token..
success := CkOAuth2_RefreshAccessToken(oauth2);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkOAuth2__lastErrorText(oauth2));
    Exit;
  end;

// Load the access token response into the json object 
CkJsonObject_Load(jsonToken,CkOAuth2__accessTokenResponse(oauth2));

// 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 (CkJsonObject_HasMember(jsonToken,'expires_on') = False) then
  begin
    dtExpire := CkDateTime_Create();
    CkDateTime_SetFromCurrentSystemTime(dtExpire);
    CkDateTime_AddSeconds(dtExpire,CkJsonObject_IntOf(jsonToken,'expires_in'));
    CkJsonObject_AppendString(jsonToken,'expires_on',CkDateTime__getAsUnixTimeStr(dtExpire,False));
  end;

// Save the new JSON access token response to a file.
// The access + refresh tokens contained in this JSON will be needed for the next refresh.
sbJson := CkStringBuilder_Create();
CkJsonObject_putEmitCompact(jsonToken,False);
CkJsonObject_EmitSb(jsonToken,sbJson);
CkStringBuilder_WriteFile(sbJson,'qa_data/tokens/hmrc.json','utf-8',False);

Memo1.Lines.Add('OAuth2 authorization granted!');
Memo1.Lines.Add('New Access Token = ' + CkOAuth2__accessToken(oauth2));

CkJsonObject_Dispose(jsonToken);
CkOAuth2_Dispose(oauth2);
    CkDateTime_Dispose(dtExpire);
CkStringBuilder_Dispose(sbJson);

end;