Program.cs

using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using PhoneEdit.Data;

var builder = WebApplication.CreateBuilder(args);

var identityContextSecrets = builder.Configuration.GetConnectionString("IdentityContext") ?? 
                             throw new InvalidOperationException("Connection string 'IdentityContext' not found.");
var phoneBookContextSecrets = builder.Configuration.GetConnectionString("PhoneBookContext") ?? 
                              throw new InvalidOperationException("Connection string 'PhoneBookContext' not found.");
        
builder.Services.AddDbContext<ApplicationDbContext>(options => 
    options.UseSqlite(identityContextSecrets));
    
builder.Services.AddDbContext<PhonebookContext>(options => 
    options.UseMySql(phoneBookContextSecrets,ServerVersion.AutoDetect(phoneBookContextSecrets)));

builder.Services.AddDatabaseDeveloperPageExceptionFilter();

builder.Services.AddDefaultIdentity<IdentityUser>()
    .AddEntityFrameworkStores<ApplicationDbContext>();

builder.Services.Configure<IdentityOptions>(options =>
{
    options.Password.RequireDigit = false;
    options.Password.RequireLowercase = false;
    options.Password.RequireNonAlphanumeric = false;
    options.Password.RequireUppercase = false;
    options.Password.RequiredLength = 6;
    options.Password.RequiredUniqueChars = 3;
});

builder.Services.Configure<DefaultUserOptions>(builder.Configuration.GetSection("DefaultUser"));

builder.Services.AddControllersWithViews();
builder.Services.AddRazorPages();

if (builder.Environment.IsDevelopment())
{
    builder.Services.AddDatabaseDeveloperPageExceptionFilter();
}

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseMigrationsEndPoint();
}
else
{
    app.UseExceptionHandler("/Home/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.UseCookiePolicy();

app.UseRouting();

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

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

app.MapRazorPages();

using (var scope = app.Services.CreateScope())
{
    var appDbContext = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
    var pendingAppDbContextMigrations = appDbContext.Database.GetPendingMigrations().ToList();

    if (pendingAppDbContextMigrations.Count > 0)
    {
        appDbContext.Database.Migrate();
    }
    
    await SampleData.CreateDefaultUser(scope.ServiceProvider);
}

app.Run();