CustomAuthenticationStateProvider.cs

using System.Security.Claims;
using Microsoft.AspNetCore.Components.Authorization;

namespace demo {

    public class CustomAuthenticationStateProvider : AuthenticationStateProvider
    {
        public CustomAuthenticationStateProvider()
        {
            this.CurrentUser = this.GetAnonymous();
        }

        private ClaimsPrincipal CurrentUser { get; set; }

        private ClaimsPrincipal GetUser(string userName, string id, string role)
        {
            var identity = new ClaimsIdentity(new[]
            {
                new Claim(ClaimTypes. Sid, id),
                new Claim(ClaimTypes.Name, userName),
                new Claim(ClaimTypes.Role, role)
            }, "Authentication type");
            return new ClaimsPrincipal(identity);
        }

        private ClaimsPrincipal GetAnonymous()
        {
            var identity = new ClaimsIdentity(new[]
            {
                new Claim(ClaimTypes.Sid, "0"),
                new Claim(ClaimTypes.Name, "Anonymous"),
                new Claim(ClaimTypes.Role, "Anonymous")
            }, null);
            return new ClaimsPrincipal(identity);
        }

        public override Task<AuthenticationState> GetAuthenticationStateAsync()
        {
            var task = Task.FromResult(new AuthenticationState(this.CurrentUser));
            return task;
        }

        public Task<AuthenticationState> ChangeUser(string username, string id, string role)
        {
            this.CurrentUser = this.GetUser(username, id, role);
            var task = this.GetAuthenticationStateAsync();
            this.NotifyAuthenticationStateChanged(task);
            return task;
        }

        public Task<AuthenticationState> Logout()
        {
            this.CurrentUser = this.GetAnonymous();
            var task = this.GetAuthenticationStateAsync();
            this.NotifyAuthenticationStateChanged(task);
            return task;
        }
    }

}