Exception Handling

This feature allows adding custom Exception Handlers.

app.Features.AddExceptionHandling(...);

Problem Details

This feature implementation adds .NET ProblemDetails services with a custom IExceptionHandler implementation that loops through Baked.IExceptionHandler services and uses first matching handler for current exception. It also adds a custom middleware that logs exceptions.

c => c.ProblemDetails(
  typeUrlFormat: "https://my-service.com/errors/{0}",
  showUnhandled: true
)

More to find at RFC 7807 and Handle errors in ASP.NET Core.

By default this feature handles following exceptions;

• AuthenticationException which returns 401 status code
• UnauthorizedAccessExceptionHandler which returns 403 status code
• HandledException which returns 400 status code unless overridden

HandledException is an opinionated abstraction which helps providing necessary data for a handled exception result. Below is a sample for creating a user defined exception;

public class CustomHandledException(string message)
    : HandledException(message);

All remaining exceptions will be handled by the UnhandledExceptionHandler fallback, which returns a 500 result with exception type as title and a simple detail message.

{
  "type": "https://baked.mouseless.codes/errors/invalid-operation",
  "title": "Invalid Operation",
  "status": 500,
  "detail": "An unexpected error has occured. Please contact the administrator."
}

Adding Custom Exception Handlers

To add a custom exception handler, you can create a Baked.IExceptionHandler implementation and register it in ConfigurationOverriderFeature.

Below is a sample for how to create and register an exception handler

//
// Create a custom exception handler implementation
//
public class SampleExceptionHandler : IExceptionHandler
{
    public bool CanHandle(Exception ex) => ex is InvalidOperationException;
    public ExceptionInfo Handle(Exception ex) => new(ex, (int)HttpStatusCode.BadRequest, ex.Message);
}

//
// Add to service collection in ConfigurationOverriderFeature
//
public class ConfigurationOverriderFeature : IFeature
{
    public void Configure(LayerConfigurator configurator)
    {
        configurator.ConfigureServiceCollection(services =>
        {
            services.AddSingleton<IExceptionHandler, SampleExceptionHandler>();
        });
    }
}