QAbstractOAuth2::refreshToken() returns an empty string when the QOAuth2AuthorizationCodeFlow::granted signal is emitted.

Hossein2000

In the code below, the authentication process is performed by QOAuth2AuthorizationCodeFlow.
This code works correctly to get the access token, but it does not return the refresh token.

#include "qoauth2test.h"
QOAuth2Test::QOAuth2Test(QObject *parent) : QObject(parent)
{
    // Launch browser for authorization request
    connect(&google, &QOAuth2AuthorizationCodeFlow::authorizeWithBrowser,
            &QDesktopServices::openUrl);
    // Receive answer from authorization request process
    connect(&google, &QOAuth2AuthorizationCodeFlow::granted, this, &QOAuth2Test::onGranted);

    QString authUri = "https://accounts.google.com/o/oauth2/v2/auth";
    QString clientId = "XXXX";
    QString tokenUri = "https://accounts.google.com/o/oauth2/token";
    QString clientSecret = "XXXX";
    QString scope = "https://www.googleapis.com/auth/drive";
    quint16 port = 8080;
    google.setAuthorizationUrl(authUri);
    google.setClientIdentifier(clientId);
    google.setAccessTokenUrl(tokenUri);
    google.setClientIdentifierSharedKey(clientSecret);
    google.setScope(scope);

    google.setModifyParametersFunction([&](QAbstractOAuth::Stage stage, QVariantMap* parameters) {
        // Percent-decode the "code" parameter so Google can match it
        if (stage == QAbstractOAuth::Stage::RequestingAccessToken)
        {
            QByteArray code = parameters->value("code").toByteArray();
            (*parameters)["code"] = QUrl::fromPercentEncoding(code);
        }
    });

    auto replyHandler = new QOAuthHttpServerReplyHandler(port, this);
    google.setReplyHandler(replyHandler);
}

void QOAuth2Test::grant()
{
    google.grant();
}

void QOAuth2Test::onGranted()
{
    accessToken = google.token();
    qInfo() << "access Token:"<< accessToken;
    refreshToken = google.refreshToken();
    qInfo() << "refresh Token:"<< refreshToken;
}

Please tell me if anyone knows the solution.
Thank you.

Hossein2000

I found the answer
You need to replace

connect(&google, &QOAuth2AuthorizationCodeFlow::authorizeWithBrowser,
            &QDesktopServices::openUrl);

with

connect(this->google, &QOAuth2AuthorizationCodeFlow::authorizeWithBrowser, [=](QUrl url) {
        QUrlQuery query(url);

        query.addQueryItem("prompt", "consent");      // Param required to get data everytime
        query.addQueryItem("access_type", "offline"); // Needed for Refresh Token (as AccessToken expires shortly)
        url.setQuery(query);
        QDesktopServices::openUrl(url);
    });

SGaist

Hi and welcome to devnet,

Glad you found a solution and thanks for sharing !

Would you mind explaining how you got the solution ?

Hossein2000

@SGaist
Thanks . you're welcome
I stumbled this webpage accidentally, where Mr. Chilarai Mushahary had done exactly what I was looking for.