Get current (logged) user in ASP.NET Core 3.0 .razor page

Question

I\'m testing the waters with a blazer server-side app and trying to get the logged user in a .razor page. This

UserManager.GetUserAsync(User)

Answer 1

What I did:

1. added this to Startup.ConfigureServices

services.AddHttpContextAccessor();

2. used this to get the username in my .razor page, these 2 lines first

@inject UserManager<WebPageUser> UserManager
@inject IHttpContextAccessor HttpContextAccessor

3. then the call to show the username like this:

<p>Hello @UserManager.GetUserName(HttpContextAccessor.HttpContext.User)</p>

Answer 2

If you surround your code with the AuthorizeView component you can get access to a context object that supplies the current user.

<AuthorizeView>
    <Authorized>
        <h1>Hello, @context.User.Identity.Name!</h1>
        <p>You can only see this content if you're authenticated.</p>
    </Authorized>
    <NotAuthorized>
        <h1>Authentication Failure!</h1>
        <p>You're not signed in.</p>
    </NotAuthorized>
</AuthorizeView>

If you don't want to use that approach you can request a cascading parameter called authenticationStateTask, which is provided by the CascadingAuthenticationState.

@page "/"

<button @onclick="@LogUsername">Log username</button>

@code {
    [CascadingParameter]
    private Task<AuthenticationState> authenticationStateTask { get; set; }

    private async Task LogUsername()
    {
        var authState = await authenticationStateTask;
        var user = authState.User;

        if (user.Identity.IsAuthenticated)
        {
            Console.WriteLine($"{user.Identity.Name} is authenticated.");
        }
        else
        {
            Console.WriteLine("The user is NOT authenticated.");
        }
    }
}