Program.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.AspNetCore.Identity;
using System.Text.Json.Serialization;

// Connection info stored in appsettings.json
IConfiguration configuration = new ConfigurationBuilder()
    .AddJsonFile("appsettings.json")
    .Build();

var builder = WebApplication.CreateBuilder(args);
// Ignore circular reference cycles
builder.Services.AddControllersWithViews().AddJsonOptions(x =>
  x.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles);
// Register the DataContext service
builder.Services.AddDbContext<DataContext>(options => options.UseSqlServer(configuration["Data:Northwind:ConnectionString"]));
builder.Services.AddDbContext<AppIdentityDbContext>(options => options.UseSqlServer(configuration["Data:AppIdentity:ConnectionString"]));
builder.Services.AddIdentity<AppUser, IdentityRole>().AddEntityFrameworkStores<AppIdentityDbContext>().AddDefaultTokenProviders();
var app = builder.Build();

app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthentication();
app.UseAuthorization();

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

app.Run();