Startup.cs

using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Components.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using BlazorApp.Areas.Identity;
using BlazorApp.Data;
using BlazorApp.Services;

namespace BlazorApp
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<ApplicationDbContext>(options =>
                options.UseSqlServer(
                    Configuration.GetConnectionString("DefaultConnection")));
            services.AddHttpClient<ApiService>(client =>
            {
                client.BaseAddress = new Uri("http://localhost");
            });
            services.AddDefaultIdentity<IdentityUser>()
                .AddRoles<IdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>();
            services.AddRazorPages();
            services.AddServerSideBlazor();
            services.AddScoped<AuthenticationStateProvider, RevalidatingIdentityAuthenticationStateProvider<IdentityUser>>();
            services.AddSingleton<WeatherForecastService>();
            services.AddTransient<IToDoListService, ToDoListService>();
            services.AddTransient<ICascadingDropdownService, CascadingDropdownService>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IServiceProvider serviceProvider)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
                endpoints.MapBlazorHub();
                endpoints.MapFallbackToPage("/_Host");
            });
            //CreateUserAndRoles(serviceProvider).Wait();
        }

        private async Task CreateUserAndRoles(IServiceProvider serviceProvider)
        {
            //initializing custom roles   
            var RoleManager = serviceProvider.GetRequiredService<RoleManager<IdentityRole>>();
            var UserManager = serviceProvider.GetRequiredService<UserManager<IdentityUser>>();
            string[] roleNames = { "Admin", "User" };
            IdentityResult roleResult;

            foreach (var roleName in roleNames)
            {
                var roleExist = await RoleManager.RoleExistsAsync(roleName);
                if (!roleExist)
                {
                    //create the roles and seed them to the database: Question 1  
                    roleResult = await RoleManager.CreateAsync(new IdentityRole(roleName));
                }
            }

            IdentityUser user = await UserManager.FindByEmailAsync("admin@blogofpi.com");

            if (user == null)
            {
                user = new IdentityUser()
                {
                    UserName = "admin@blogofpi.com",
                    Email = "admin@blogofpi.com",
                };
                await UserManager.CreateAsync(user, "Test@579");
            }
            await UserManager.AddToRoleAsync(user, "Admin");


            IdentityUser user1 = await UserManager.FindByEmailAsync("jane.doe@blogofpi.com");

            if (user1 == null)
            {
                user1 = new IdentityUser()
                {
                    UserName = "jane.doe@blogofpi.com",
                    Email = "jane.doe@blogofpi.com",
                };
                await UserManager.CreateAsync(user1, "Test@246");
            }
            await UserManager.AddToRoleAsync(user1, "User");

        }
    }
}