kakao developers

Auto-login from Kakao Talk

The Auto-login from Kakao Talk (Auto-login, for short) is an extended feature of Kakao Login, which allows you to show a different page depending on the response. This feature allows for a more efficient and convenient service for users according to their signup status when accessing your service page in the Kakao Talk in-app browser.

The Auto-login process is broken down into three steps.

Here is a sequence diagram showing the Auto-login process.

Here is one of the Auto-login scenarios. As an example, let's see a product page that is commonly shared through Kakao Talk.

• See the browser information to check if the user accessed the page through the Kakao Talk in-app browser.
• If the user has accessed the page through the Kakao Talk in-app browser, add prompt=none in the login request.
• If the user has signed up through Kakao Sync, you will get an authorization code and show a product description page in a logged-in state. In this case, users do not need to log in to buy the product on the page.
• If the user has not signed up, an error returns. In this case, show the user the product page in a logged-out state. If the user wants to log in to make a purchase, prompt the user to log in, not using the Auto-login feature.

Web

After checking that the user browser is the Kakao Talk in-app browser, request an authorization code using a REST API. To use the Auto-login feature, you must add prompt=none in the request. If not, general Kakao Login proceeds instead of the Auto-login.

You can get the authorization code through redirect_uri that the Kakao authorization server passes to as the query string.

If a user has signed up with the Kakao Account through Kakao Sync, only the authorization code is returned in the response. In this case, show the user your service page in a logged-in state after requesting an access token and a refresh token with the authorization code.

On the other hand, if a user has not signed up yet, an error is returned. In this case, show the user your service page in a logged-out state. You also need to implement the login process without Auto-login when a user takes an action that requires login or signup.

GET /oauth/authorize?client_id=${REST_API_KEY}&redirect_uri=${REDIRECT_URI}&response_type=code&prompt=none HTTP/1.1
Host: kauth.kakao.com

HTTP/1.1 302 Found
Content-Length: 0
Location: ${REDIRECT_URI}?code=${AUTHORIZATION_CODE}

HTTP/1.1 302 Found
Content-Length: 0
Location: ${REDIRECT_URI}?error=consent_required&error_description=user%20consent%20required.

Legacy Android

For Auto-login, add auto_login to extraParams, and set it to true. The auto_login parameter should be Map type, and use the constants only supported by com.kakao.auth.StringSet as values.

Set AuthType to KAKAO_TALK_ONLY because Auto-login only works from the Kakao Talk in-app browser.

If a user successfully logs in, the user is redirected to a service page in a logged-in state.

import com.kakao.auth.StringSet;

public class SampleLoginActivity extends BaseActivity {
    private SessionCallback callback;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sample_login);

        callback = new SessionCallback();
        Session.getCurrentSession().addCallback(callback); // Add callback

        Map<String, String> extraParams = new HashMap<>();
        extraParams.put(StringSet.auto_login, "true");

        Session.getCurrentSession().open(AuthType.KAKAO_TALK_ONLY, this, extraParams); // Pass KAKAO_TALK_ONLY as a parameter. Otherwise, the webView login is executed if Kakao Talk has not installed.  
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (Session.getCurrentSession().handleActivityResult(requestCode, resultCode, data)) {
            return;
        }

        super.onActivityResult(requestCode, resultCode, data);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Session.getCurrentSession().removeCallback(callback); // Remove callback
    }

    private class SessionCallback implements ISessionCallback {

        @Override
        public void onSessionOpened() {
            // Login success
        }

        @Override
        public void onSessionOpenFailed(KakaoException exception) {
            // Login fail
        }
    }
}

Legacy iOS

To use the Auto-login feature, you need to call canOpenURL that checks if Kakao Talk has been installed, and set authType to KOAuthType.talk. After that, pass KOSessionAutoLoginParameterKey as parameters.

// Check if Kakao Talk has been installed
if UIApplication.shared.canOpenURL(URL(string: "kakaokompassauth://")!) {

    // For Auto-login, add `KOSessionAutoLoginParameterKey`
    let parameters = [KOSessionAutoLoginParameterKey: "true"]

    // Simple login without a dialog to choose a login method 
    let authTypes = [NSNumber(value: KOAuthType.talk.rawValue)]

    // Proceed login
    KOSession.shared()?.open(completionHandler: { (error) in

        if error != nil {
            // Change to a logged-in state

        } else {
            // If login fails or other error occurs, Auto-login is not available.
        }

    }, parameters: parameters, authTypes: authTypes)

} else {
    // If Kakao Talk has not been installed, Auto-login is not available.
}

Considering the Auto-login is only available in the Kakao Talk in-app browser, you need to handle an error exception by showing the user the service page in a logged-out state if Kakao Talk has not been installed on the user's device. There is also the error exception that a user has not yet signed up for KaKao Talk. In this situation, you need to handle the expectation as you would a logged-out state.

See more

Web

Reference for REST APIDownload JavaScript SDKReference for JavaScript SDKoutlink

Android

Download Legacy Android SDKAPI Reference for Legacy Android outlink

iOS

Download Legacy iOS SDKAPI Reference for Legacy iOS outlink