Program.cs

using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Example.Data;

var builder = WebApplication.CreateBuilder(args);

if (builder.Environment.IsProduction())
{
    // PostgreSQL for production
    var connectionString = builder.Configuration.GetConnectionString("pgConnection");
    builder.Services.AddDbContext<ApplicationDbContext>(options =>
        options.UseNpgsql(connectionString));
}
else {
    // SQLite for development
    builder.Services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlite("Data Source=app.db"));
}


builder.Services.AddControllersWithViews();

// Add identity services
builder.Services.AddDatabaseDeveloperPageExceptionFilter();
builder.Services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddEntityFrameworkStores<ApplicationDbContext>();

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.MapRazorPages();

app.Run();