Azure App Service Easy Auth

Question

I have an Azure mobile backend set up with easy auth for facebook and google authentication and it works as expected.

Every time a user signs in with any of the supported providers, I want to be able to verify if it's a new user or not (e-mail not in database), without make an additional call from client. Is this possible?

Brando Zhang Brando Zhang · Accepted Answer · 2017-09-20T06:37:46

Every time a user signs in with any of the supported providers, I want to be able to verify if it's a new user or not (e-mail not in database), without make an additional call from client. Is this possible?

As far as I know, we couldn't directly verify if it's a new user or not.

No matter you use server flow or client flow, easy auth will just return access token for the client to access the mobile backend resources, it will not check the user is new or old.

If you want to achieve this requirement, you need write your own logic.

You could write codes after the user login successfully.

For example, facebook login.

If you the use have login successfully,you could call GetAppServiceIdentityAsync extension method to get the login credentials, which include the access token needed to make requests against the Facebook Graph API.

// Get the credentials for the logged-in user.
var credentials =
    await this.User
    .GetAppServiceIdentityAsync<FacebookCredentials>(this.Request);

if (credentials.Provider == "Facebook")
{
    // Create a query string with the Facebook access token.
    var fbRequestUrl = "https://graph.facebook.com/me/feed?access_token="
        + credentials.AccessToken;

    // Create an HttpClient request.
    var client = new System.Net.Http.HttpClient();

    // Request the current user info from Facebook.
    var resp = await client.GetAsync(fbRequestUrl);
    resp.EnsureSuccessStatusCode();

    // Do something here with the Facebook user information.
    var fbInfo = await resp.Content.ReadAsStringAsync();
}

Then you could check the database according to the user information.

More details about how to get user information in server side, you could refer to How to: Retrieve authenticated user information.

Azure App Service Easy Auth

1 Answers