Retornator

Retornator is a C# library for handling the return of business logic data and its possible errors. It is very coupled with ASP.NET Core but not required to do so, we recommend using MediatR as well.

Installation

dotnet add package Nudes.Retornator.AspnetCore

Usage

Inject necessary services on Program.cs:

builder.Services.AddControllers().AddRetornator();

This will inject an RetornatorResultOutputFormatter to your ASP.Net list of outputformatters

Create your service returning ResultOf<T> or Result where T is your DTO type. From your service you will be able to return an Error or your Result (type of T) and implicit conversions will take place to ResultOf<T> or Result

class MyResult
{
    public string Id { get; set; }
    public string SomeOtherValue { get; set; }
}

In your business logic handler, return an instance of that class or throw some errors using .Throw(Error):

public ResultOf<MyResult> HandleMyBusinessLogic(SomeInputData data)
{
    // ...
    // do some business logic here


    // something wrong with the request or with the logic per se? then throw some errors
    return new SomeError();

    // or do you need to add more information like field errors?
    return new SomeError()
            .AddFieldError("FieldName", "The field name must have at least 30 characters.")
            .AddFieldError("Id", "The field Id cannot be altered."));

    // everything according to the plan? then return your result
    return new MyResult();
}

In your controller, map the request and send to your business logic handler, we recommend using MediatR to do that (check the samples):

[HttpGet("someroute")]
public async Task<ResultOf<MyResult>> SomeAction(SomeInputData data)
{
    var result = await businessLogicHandler.HandleMyBusinessLogic(data);
    return result;
}

Retornator will handle your result and if there is any error on it the error will be serialized; if everything goes well it will serialize your result class.

If you are using ASP.NET Core you will need a way to translate errors to the according HTTP Status Code. For that you can use Retornator base errors and the ErrorHttpTranslatorBuilder or create and inject your own. To use it, on Program.cs add:

builder.Services
    .AddErrorTranslator(ErrorHttpTranslatorBuilder.Default);

If you need help to create your own, check our samples.

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.