(Unicode C++) Refresh HMRC OAuth2 Access Token

Demonstrates how to refresh an HMRC access token.

Chilkat C/C++ Library Downloads
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#include <CkJsonObjectW.h>
#include <CkOAuth2W.h>
#include <CkDateTimeW.h>
#include <CkStringBuilderW.h>

void ChilkatSample(void)
    {
    // 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.

    CkJsonObjectW jsonToken;
    bool success = jsonToken.LoadFile(L"qa_data/tokens/hmrc.json");
    if (success != true) {
        wprintf(L"Failed to load hmrc.json\n");
        return;
    }

    // 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": "..."
    // }

    CkOAuth2W oauth2;

    oauth2.put_TokenEndpoint(L"https://test-api.service.hmrc.gov.uk/oauth/token");

    // Replace these with actual values.
    oauth2.put_ClientId(L"HMRC-CLIENT-ID");
    oauth2.put_ClientSecret(L"HMRC-CLIENT-SECRET");

    // Get the "refresh_token"
    oauth2.put_RefreshToken(jsonToken.stringOf(L"refresh_token"));

    // Send the HTTP POST to refresh the access token..
    success = oauth2.RefreshAccessToken();
    if (success != true) {
        wprintf(L"%s\n",oauth2.lastErrorText());
        return;
    }

    // Load the access token response into the json object 
    jsonToken.Load(oauth2.accessTokenResponse());

    // 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 (jsonToken.HasMember(L"expires_on") == false) {
        CkDateTimeW dtExpire;
        dtExpire.SetFromCurrentSystemTime();
        dtExpire.AddSeconds(jsonToken.IntOf(L"expires_in"));
        jsonToken.AppendString(L"expires_on",dtExpire.getAsUnixTimeStr(false));
    }

    // 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.
    CkStringBuilderW sbJson;
    jsonToken.put_EmitCompact(false);
    jsonToken.EmitSb(sbJson);
    sbJson.WriteFile(L"qa_data/tokens/hmrc.json",L"utf-8",false);

    wprintf(L"OAuth2 authorization granted!\n");
    wprintf(L"New Access Token = %s\n",oauth2.accessToken());
    }