CSharpFunctionalExtensions.HttpResults 0.0.1

CSharpFunctionalExtensions.HttpResults

Extensions for CSharpFunctionalExtensions to map Results to HttpResults in your MinimalApi

Installation

Available on NuGet.

dotnet add package CSharpFunctionalExtensions.HttpResults

or

PM> Install-Package CSharpFunctionalExtensions.HttpResults

Usage

This library provides you extension methods to map the following types to HttpResults:

• Result
• Result<T>
• Result<T,E>
• UnitResult<E>

These methods are available:

For almost every method you can override the default status codes for Success/Failure by passing corresponding int values.

By default, failures get mapped to a ProblemHttpResult. If you want your own mapping logic or even don't want to map to HttpErrors read on.

Custom errors

This library uses a Source Generator to generate extension methods for your own custom error types when using Result<T,E> or UnitResult<E>.

1. First create a custom error type that implements IResultError

   public class UserNotFoundError : IResultError
   {
       public required string UserId { get; init; }
   }
   

2. Create a mapper that implements IResultErrorMapper which maps this custom error type to another type that you want to return in your web api:

   public class UserNotFoundErrorMapper : IResultErrorMapper<UserNotFoundError, Microsoft.AspNetCore.Http.IResult>
   {
       public Func<UserNotFoundErrorMapper, Microsoft.AspNetCore.Http.IResult> Map => error => {
           var problemDetails = new ProblemDetails
           {
               Status = 404,
               Title = "User not found",
               Type = "https://tools.ietf.org/html/rfc9110#section-15.5.5",
               Detail = $"The user with ID {error.UserId} couldn't be found.
           };
   
           return TypedResults.Problem(problemDetails);  
       };
   }
   

3. Use the generated extension method:

   app.MapGet("/users/{id}", (string id) => {
       return userRepository.find(id) //Result<User,UserNotFoundError>
           .ToHttpResult();
   });
   

Make sure that every IResult implementation only has exactly one corresponding IResultMapper implementation.