ExtendedProgram.cs

Program.cs

using System.Text.Json.Serialization;
using AotWebApi;
using Microsoft.Extensions.Options;

var builder = WebApplication.CreateSlimBuilder(args);

builder.Services.ConfigureHttpJsonOptions(options =>
{
    options.SerializerOptions.TypeInfoResolverChain.Insert(0, AppJsonSerializerContext.Default);
});

/* Use configuration binding. */
builder.Services
    .AddOptions<AppSettings>()
    .BindConfiguration(nameof(AppSettings));
/* Use configuration binding.*/

var app = builder.Build();

var sampleTodos = TodoGenerator.GenerateTodos();

var todosApi = app.MapGroup("/todos");

/* Use configuration binding. */
todosApi.MapGet("/", (IOptions<AppSettings> settings) => sampleTodos.Take(settings.Value.MaxReturnCount));
/* Use configuration binding. */

todosApi.MapGet("/{id}", (int id) =>
    sampleTodos.FirstOrDefault(a => a.Id == id) is { } todo
        ? Results.Ok(todo)
        : Results.NotFound());

app.Run();

[JsonSerializable(typeof(IEnumerable<Todo>))]
[JsonSerializable(typeof(AppSettings))]
internal partial class AppJsonSerializerContext : JsonSerializerContext
{
}

/* Use configuration binding */
internal class AppSettings
{
    public int MaxReturnCount { get; set; }
}
/* Use configuration binding */