Resultix 1.0.0

Resultix

Stupidly simple result pattern for .NET

Why use this library?

Many result pattern libraries have confusing configuration and lots of customisation options, which can be overwhelming. This library is for you if you want a barebones, easy to use and understand result pattern in .NET.

Installation

Standard installation through NuGet.

NuGet CLI:

Install-Package Resultix

.NET core CLI

dotnet add package Resultix

Quick start

Returning a result from a function

You can use the out of the box Result<T> type, which by default has an error type of System.Exception. Or you can define your own error type, by using the generic overload Result<TResult, TError>.

Consider the following code. We have a simple class called Movie and a function GetMovie() which returns Result<Movie>.

using System;
using Resultix;

public class Movie
{
    public int Id { get; set; }

    public string Name { get; set; }
}

public class MovieService
{
    // demo class - inner workings omitted for brevity

    public Result<Movie> GetMovie(string movieName)
    {
        if (string.IsNullOrWhiteSpace(movieName))
            return new ArgumentException($"{nameof(movieName)} cannot be null or whitespace"); // notice Exception is being returned, not thrown

        var movie = _db.GetMovieByName(movieName);

        if (movie is null)
            return default;

        return movie;
    }
}

When returning types from a function with a signature of Result, implicit operators in the Result struct allow you to return the following types

• Any instance of TResult - which indicates a success result
• Any instance of TError or (System.Exception when using Result<TResult>) - which indicates a failure
• default or default(TResult) - which indicates a "None" result.

Resolving a result

Now you have a function returning a Result, you can call that function and perform different actions depending on the result. Consider the following code.

public IHttpActionResult GetMovie(string movieName)
{
    var result = GetMovie(movieName);

    return result.Match(movie => Ok(movie), // onSuccess
                        error => BadRequest(error.Message) // onError
                        () => NotFound()); //onNone
}

Calling the Match() function will call one of the 3 lambdas passed in, depending on the result. The first parameter, onSuccess gets executed when the Result is successful. The second parameter onError gets called when TError is returned from the GetMovie function. The 3rd and final parameter, onNone gets called when default is returned from GetMovie().

The is an overload for Match() which takes in System.Action as the parameter types instead, for when you don't want to return a result from Match(). There are also async versions available, named MatchAsync(), which follow the same concept.

Optional configuration options

There is currently only one configuration option. This property lives in the ResultConfig class and is called EnforceMatches. When set to true it will cause an exception to be thrown if null is passed in for any of the lambdas in the Match() and MatchAsync() functions. The default value, false, means that you can pass null into the Match() and MatchAsync() functions if you don't want to handle certain results. This setting was designed to be set once, at application start-up.