GetExternalLoginInfoAsync returns null dotnet core 2.0

问题

I'm trying to setup Facebook authentication with dot-net core 2.0, but in my ExternalLoginCallbackAsync method, I'm always getting null as a response I have followed the documentation and so far this is what I've done:

in my ConfigureServices in the startup file:

services.AddAuthentication(
            options => options.DefaultAuthenticateScheme = CookieAuthenticationDefaults.AuthenticationScheme);

services.AddAuthentication().AddFacebook(
    f => {
        f.AppId = Configuration["facebook-app-id"];
        f.AppSecret = Configuration["facebook-app-secret"];
});

in my login controller:

public IActionResult ExternalLogin(string provider)
        {

            var authProperties = new AuthenticationProperties
            {
                RedirectUri = Url.Action("ExternalLoginCallbackAsync", "Login")                
            };
            return Challenge(authProperties,provider);
        }

in my ExternalLoginCallbackAsync method when I do

var info = await _signInManager.GetExternalLoginInfoAsync();

any hint why am I always getting null?

thanks

回答1:

I looked at the SignInManager code as Lasse Vabe Rolstad suggested and for me, a key was missing in the auth properties so I had to add it manually like this:

 var authProperties = new AuthenticationProperties
 {
     RedirectUri = Url.Action("ExternalLoginCallbackAsync", "Login"),
     Items = { new KeyValuePair<string, string>("LoginProvider",provider) }
 };

来源：https://stackoverflow.com/questions/45852188/getexternallogininfoasync-returns-null-dotnet-core-2-0