Minimal Web API With .NET 9

1. No support for filters: For example, no support for IAsyncAuthorizationFilter, IAsyncActionFilter, IAsyncExceptionFilter, IAsyncResultFilter, and IAsyncResourceFilter.
2. No support for model binding, i.e. IModelBinderProvider, IModelBinder. Support can be added with a custom binding shim.
3. No support for binding from forms. This includes binding IFormFile. We plan to add support for IFormFile in the future.
4. No built-in support for validation, i.e. IModelValidator
5. No support for application parts or the application model. There's no way to apply or build your own conventions.
6. No built-in view rendering support. We recommend using Razor Pages to render views.
7. No support for JsonPatch
8. No support for OData
9. No support for ApiVersioning. See this issue for more details.

To demonstrate the minimal API in .NET 6, I have created a sample here,

With the following APIs,

REST APIs follow standard HTTP Verbs like GET, POST, PUT, DELETE, and PATCH, which are basically CRUD operations on an object. The APIs are arranged to form an internet resource. For example, in the above example, we have a resource as “todoitem” which can be created, modified, and deleted using APIs, and the URL format is formed accordingly.

using Microsoft.EntityFrameworkCore;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddDbContext < TodoDb > (opt => opt.UseInMemoryDatabase("TodoList"));
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment()) {
    app.UseSwagger();
    app.UseSwaggerUI();
}
app.MapGet("/", () => "Hello World!");
app.MapGet("/todoitems", async (TodoDb db) => await db.Todos.ToListAsync());
app.MapGet("/todoitems/complete", async (TodoDb db) => await db.Todos.Where(t => t.IsComplete).ToListAsync());
app.MapGet("/todoitems/{id}", async (int id, TodoDb db) => await db.Todos.FindAsync(id)
    is Todo todo ? Results.Ok(todo) : Results.NotFound());
app.MapPost("/todoitems", async (Todo todo, TodoDb db) => {
    db.Todos.Add(todo);
    await db.SaveChangesAsync();
    return Results.Created($ "/todoitems/{todo.Id}", todo);
});
app.MapPut("/todoitems/{id}", async (int id, Todo inputTodo, TodoDb db) => {
    var todo = await db.Todos.FindAsync(id);
    if (todo is null) return Results.NotFound();
    todo.Name = inputTodo.Name;
    todo.IsComplete = inputTodo.IsComplete;
    await db.SaveChangesAsync();
    return Results.NoContent();
});
app.MapDelete("/todoitems/{id}", async (int id, TodoDb db) => {
    if (await db.Todos.FindAsync(id) is Todo todo) {
        db.Todos.Remove(todo);
        await db.SaveChangesAsync();
        return Results.Ok(todo);
    }
    return Results.NotFound();
});
app.Run();
class Todo {
    public int Id {
        get;
        set;
    }
    public string ? Name {
        get;
        set;
    }
    public bool IsComplete {
        get;
        set;
    }
}
class TodoDb: DbContext {
    public TodoDb(DbContextOptions < TodoDb > options): base(options) {}
    public DbSet < Todo > Todos => Set < Todo > ();
}

Conclusion

REST architecture style provides a standard way to arrange resources over the internet and a common way for clients to access and get the server data. Minimal API requires minimum code and a quick and easy way to create APIs that do not require Auth or that sit behind a gateway(with Auth) and have very minimal dependencies.

References

1. https://learn.microsoft.com/en-us/aspnet/core/tutorials/min-web-api?view=aspnetcore-9.0&tabs=visual-studio
2. https://restfulapi.net/