Avoid duplicate user creation using SSO Authentication

Question

I have created a community and created an Auth. Provider for google and linkedIn. This SSO are working correctly.

My problem is when I login using gmail a new user is created which is linked to gmail. While when I login using linked In with a new user is created.

But I don't want to create a new user if first name, last name and email are common or same. How will I do this?

For e.g. My one user is linked with gmail which has First Name = Swapnil Last Name = Kale Email = test@gmail.com

Now If I try to signup with Linked In with information as above First Name = Swapnil Last Name = Kale Email = test@gmail.com

Two duplicate records are created.

I want to avoid duplicate user creation. How will I achieve this.

What I was thinking is if more same user exist then he will be redirected to vf page to show user with same info. If user already exists then he will select his user and get logged in. Can I redirect to a VF page showing all duplicate users while authenticating?

Answer 1

If you have a Registration Handler class, you could use code similar to below to identify existing user and return.

 global class GoogleAuthRegHandler implements Auth.RegistrationHandler{

    global User createUser(Id portalId, Auth.UserData data){

        User user;

        //Gets user data based on gmail address
        user = [select Id from User where Firstname = :data.firstName AND LastName = :data.lastName limit 1];

        //more code to handle scenario where user doesn't exist already goes here
        return user;

    }
// Other handler methods go here

    }