Sisusa.ReturnTypes.ToActionResult 1.0.0

Namespace: Sisusa.ReturnTypes.WebApi

This namespace contains classes and extensions to handle failures in a Web API by converting them into appropriate HTTP responses using ActionResult.

I would have loved to have this ship as part of the Sisusa.Common.RetunTypes package but hated cluttering up that package's dependency chain - this package has an obvious dependency on Microsoft.ApnetCore.Mvc and the Sisusa packages (Data.Contracts, ReturnTypes)

Class: FailureExtensionsWebApi

A static class providing extension methods for converting IFailure objects into ASP.NET Core ActionResult instances.

Method: ToActionResult(this IFailure failure)

Converts an IFailure object into an ActionResult representing the appropriate HTTP response.

Parameters

• failure (IFailure): An object representing a failure. If null, a generic "No failure to convert." message is returned.

Returns

• ActionResult:
  • A ProblemDetails object wrapped in ObjectResult, containing the HTTP status code, failure message, and details.
  • A fallback response if failure is null.

Key Functionality

1. Extracts the InnerException from the failure object or assigns a generic exception message.
2. Creates a ProblemDetails object with:
   • Status: Determined by GetStatusCodeFromException.
   • Title: The message from the failure.
   • Detail: Detailed exception information from GetMessageDetailsFromException.
3. Returns the ProblemDetails object wrapped in an ObjectResult.

Private Method: GetMessageDetailsFromException(Exception ex)

Retrieves detailed information from an exception.

Parameters

• ex (Exception): The exception to extract details from.

Returns

• string: A detailed description of the exception including:
  • The message.
  • Inner exception message (if present).
  • Debug information (if DEBUG is enabled):
    • Source of the exception.
    • Stack trace.

Private Method: GetStatusCodeFromException(Exception ex)

Maps an exception type to an appropriate HTTP status code.

Parameters

• ex (Exception): The exception to evaluate.

Returns

• int: The HTTP status code corresponding to the exception.

Status Code Mappings

• EntityNotFoundException: 404 Not Found
• BadConnectionException: 503 Service Unavailable
• UnauthorizedAccessException: 401 Unauthorized
• DuplicateKeyException: 409 Conflict
• ArgumentException: 400 Bad Request
• NullReferenceException: 400 Bad Request
• All other exceptions: 500 Internal Server Error

Key Features

1. Graceful Error Handling:
   • Converts exceptions and failures into structured HTTP responses (ProblemDetails).
2. Detailed Debug Information:
   • Includes stack trace and source information in debug mode.
3. Custom Status Codes:
   • Uses GetStatusCodeFromException to map specific exceptions to HTTP status codes.
4. Extensibility:
   • Designed to easily extend exception handling logic by adding new mappings in GetStatusCodeFromException.

Usage Example

var failure = new CustomFailure("Something went wrong.");
var result = failure.ToActionResult();

// Use 'result' as the response in a controller action.
return result;

Most probable use case - the use case I wrote the library for.

[HttpGet("/{id:int}")]
public ActionResult<User> GetOne([FromRoute]int id)
{
    return userService
            .FindById(id)
            .MatchReturn(
                user=>Ok(user),
                err => err.ToActionResult() 
            );
}

This documentation provides an overview of the code's purpose, functionality, and usage to assist developers in understanding and utilizing the FailureExtensionsWebApi class effectively.