Back4App

Sign In with LinkedIn Tutorial

Introduction

Sign In with LinkedIn enables users to sign in to Apps using their LinkedIn accounts.

Step 1 - Create a New Back4App App

First of all, it’s necessary to make sure that you have an existing app created at Back4App. However, if you are a new user, you can check this tutorial to learn how to create one.

Step 2 - Create a new LinkedIn App

Log into your LinkedIn Developer account and click Create App and choose OAuth client ID

Choose an App name and fill the required fields such as Business email and App logo. Agree to the therms and click Create app

In your newly created App, click Verify in order to verify the ownership of the App. You must be owner or administrator of the LinkedIn page in order to verify.

In the Verification page, click Generate URL

Visit the generated Verification URL using the admin or onwer account of the company’s page in LinkedIn.

Click on Approve Verification

Make sure your App is verified

In your App, go to the Auth tab, fill the Redirect URLs field and click Update

Step 3 - Retrieve your Code

Visit the following URL, changing the values for CLIENT_ID, REDIRECT_URL and A_RANDOM_STRING for the ones you created.
The random string is to avoid CSRF attacks.

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https://www.linkedin.com/oauth/v2/authorization?response_type=code&client_id=CLIENT_ID&redirect_uri=REDIRECT_URL&state=A_RANDOM_STRING&scope=r_emailaddress

Log in with your LinkedIN account and the redirected website will have your code in the URL:

Copy the Code part of the URL only and run the following CURL command replacing the values YOUR_CODE, YOUR_CLIENT_ID, YOUR_CLIENT_SECRET and YOUR_REDIRECT_URI for the values of your application

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curl -X POST \
  https://www.linkedin.com/oauth/v2/accessToken \
  -H 'cache-control: no-cache' \
  -H 'content-type: application/x-www-form-urlencoded' \
  -d 'client_id=YOUR_CLIENT_ID&client_secret=YOUR_CLIENT_SECRET&redirect_uri=YOUR_REDIRECT_URI&code=YOUR_CODE&grant_type=authorization_code'

Run it and you should retrieve your access token:

REMEMBER: the code can be used only once. If you get an error or don’t use your token, you must re-generate your Code to be able to run it again.

Step 4 - Start the development

Now that the Sign In with LinkedIn is configured, you can start the development process.
The format for AUTHDATA is:

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{
  "linkedin": {
    "id": "user's LinkedIn id (string)",
    "access_token": "an authorized LinkedIn access token for the user",
    "is_mobile_sdk": true|false // set to true if you acquired the token through LinkedIn mobile SDK
  }
}

Here is the method for the iOS SDK:

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PFUser.logInWithAuthType(inBackground: "linkedin", authData: ["access_token":tokenString, "id": user, "is_mobile_sdk": true]).continueWith { task -> Any? in
    
}

And here for the Android SDK:

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Map<string, string, bool> authData = new HashMap<string, string, bool>(); 
authData.put("access_token", tokenString);
authData.put("id", user);
authData.put("is_mobile_sdk", true);
Task<ParseUser> t = ParseUser.logInWithInBackground("google", authData);
				t.continueWith(new Continuation<ParseUser, Void>() {
					public Void then(Task task) throws Exception {
						if (task.isCancelled()) {
							Log.w(TAG, "Task cancelled");
						} else if (task.isFaulted()) {
							Log.w(TAG, "Save FAIL" + task.getError());
							Utilities.showToast(getResources().getString(R.string.errorLogin) + task.getError(), MainActivity.this);
						} else {
							// the object was saved successfully.
							ParseUser user = (ParseUser)task.getResult();
							Log.w(TAG, "Success " + user.getObjectId() + " " + user.getUsername() + " " + user.getEmail() + " " + user.getSessionToken());
                  }
               }
            }