An opinionated look at Minimal API in .NET 6

var app = WebApplication.Create();
app.MapGet("/", () => "Hello World!");
app.Run();

var builder = WebApplication.CreateBuilder(args);

builder.AddSerilog();
builder.AddSwagger();
builder.AddAuthentication();
builder.AddAuthorization();
builder.Services.AddCors();
builder.AddStorage();

builder.Services.AddCarter();

var app = builder.Build();
var environment = app.Environment;

app
    .UseExceptionHandling(environment)
    .UseSwaggerEndpoints(routePrefix: string.Empty)
    .UseAppCors()
    .UseAuthentication()
    .UseAuthorization();

app.MapCarter();

app.Run();

$ tree
.
├── ApplicationBuilderExtensions
│   ├── ApplicationBuilderExtensions.cs
│   └── ApplicationBuilderExtensions.OpenAPI.cs
├── assets
│   └── run.http
├── Features
│   ├── HomeModule.cs
│   └── TodosModule.cs
├── GlobalUsing.cs
├── MinimalAPI.csproj
├── Program.cs
├── Properties
│   └── launchSettings.json
├── ServiceCollectionExtensions
│   ├── ServiceCollectionExtensions.Auth.cs
│   ├── ServiceCollectionExtensions.Logging.cs
│   ├── ServiceCollectionExtensions.OpenAPI.cs
│   └── ServiceCollectionExtensions.Persistence.cs
└── todos.db

namespace Microsoft.Extensions.DependencyInjection;

using Microsoft.OpenApi.Models;

public static partial class ServiceCollectionExtensions
{
    public static WebApplicationBuilder AddSwagger(this WebApplicationBuilder builder)
    {
        builder.Services.AddSwagger();

        return builder;
    }

    public static IServiceCollection AddSwagger(this IServiceCollection services)
    {
        services.AddEndpointsApiExplorer();
        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new OpenApiInfo()
            {
                Description = "Minimal API Demo",
                Title = "Minimal API Demo",
                Version = "v1",
                Contact = new OpenApiContact()
                {
                    Name = "Oleksii Nikiforov",
                    Url = new Uri("https://github.com/nikiforovall")
                }
            });
        });

        return services;
    }
}

namespace MinimalAPI;

using Dapper;
using Microsoft.Data.Sqlite;

public class TodosModule : ICarterModule
{
    public void AddRoutes(IEndpointRouteBuilder app)
    {
        app.MapGet("/api/todos", GetTodos);
        app.MapGet("/api/todos/{id}", GetTodo);
        app.MapPost("/api/todos", CreateTodo);
        app.MapPut("/api/todos/{id}/mark-complete", MarkComplete);
        app.MapDelete("/api/todos/{id}", DeleteTodo);
    }
    private static async Task<IResult> GetTodo(int id, SqliteConnection db) =>
        await db.QuerySingleOrDefaultAsync<Todo>(
            "SELECT * FROM Todos WHERE Id = @id", new { id })
            is Todo todo
                ? Results.Ok(todo)
                : Results.NotFound();

    private async Task<IEnumerable<Todo>> GetTodos(SqliteConnection db) =>
        await db.QueryAsync<Todo>("SELECT * FROM Todos");

    private static async Task<IResult> CreateTodo(Todo todo, SqliteConnection db)
    {
        var newTodo = await db.QuerySingleAsync<Todo>(
            "INSERT INTO Todos(Title, IsComplete) Values(@Title, @IsComplete) RETURNING * ", todo);

        return Results.Created($"/todos/{newTodo.Id}", newTodo);
    }
    private static async Task<IResult> DeleteTodo(int id, SqliteConnection db) =>
        await db.ExecuteAsync(
            "DELETE FROM Todos WHERE Id = @id", new { id }) == 1
            ? Results.NoContent()
            : Results.NotFound();
    private static async Task<IResult> MarkComplete(int id, SqliteConnection db) =>
        await db.ExecuteAsync(
            "UPDATE Todos SET IsComplete = true WHERE Id = @Id", new { Id = id }) == 1
            ? Results.NoContent()
            : Results.NotFound();
}

public class Todo
{
    public int Id { get; set; }
    public string? Title { get; set; }
    public bool IsComplete { get; set; }
}

// FROM
app.MapGet("/todos", async (SqliteConnection db) =>
    await db.QueryAsync<Todo>("SELECT * FROM Todos"));

// TO
app.MapGet("/api/todos", GetTodos);

async Task<IEnumerable<Todo>> GetTodos(SqliteConnection db) =>
        await db.QueryAsync<Todo>("SELECT * FROM Todos");

builder.Services.AddCarter();
// ...
app.MapCarter();