Does .NET 6 support pipelines of business logic – like middleware for a request, but for custom logic? – Asp.net

I have a number of reusable business logic steps which will be re-used in various web endpoints. I’m trying to see if there’s a nice way in .NET 6 to ‘chain’ these reusable business logic code (think, classes where each class does just one logic step).

It’s like how .NET has ‘middleware’ for web apps. Only in this instance, I wish to hit an endpoint then do all the steps in my custom pipeline, with the steps hardcoded for that endpoint.

here’s a high level summary.

• Each ‘flow’ has a number of steps
• A single endpoint ‘invokes’ as specific flow .. which then steps through each step -until some business logic fails some check- which stops continuing and bubbles back with the error message or view.

for example.

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddScoped<IUserRegistration>(_ =>
{
    new MyPipeline()
        .AddStep(newUser => ValidateUserData(newUser)) // userData is from the POST request body.
        .AddStep(user => CheckIfUserExists(user)) // Check if the user exists in the db
        .AddStep(user => CreateUser(user));
});
builder.Services.AddScoped<IEnrollForCourse>(_ =>
{
    new MyPipeline()
        .AddStep(user => CheckIfUserExists(user)) // Check if the user exists in the db
        .AddStep(course => CheckIfTheCourseExists(course)) // Does the uni course, exist?
        .AddStep((user, course) => EnrollUserToCourse(user, course));
});

var app = builder.Build();


app.MapPost("/register", async (NewUserModel newUser, IUserRegistration userRegistration) =>
{
    var viewResult = await userRegistration.Execute(newUser);

    return viewResult; // 200-OK | 400-BadRequest
});

app.MapPost("/enroll", async (EnrollModel enroll, IEnrollForCourse enrollForCourse) =>
{
    var viewResult = await enrollForCourse.Execute(enroll);

    retyrn viewResult; // 204-NoContent | 400-BadRequest
});

app.Run();

So there’s heaps of problems with the above, but the general idea there.

Is this a solved problem, in .NET already? Surely this isn’t new.

EDIT: Of course, I would usually just use a single class with if/else checks .. which then call the various business logic. Yes, I know. We have that -now- and if just feels really large and unwieldy and I’m trying to see if this can be refactored into nicer, re-usable components.

Also, I don’t want to use Logic Apps .. which is a similar concept by Microsoft.

NOTE: I’m using users/course/uni etc as a simplistic example for demo/question purposes.