ProblemNet

ProblemNET is a middleware library that implements rfc7807. The middleware catches all exceptions and handles according to exception type.
For more information: https://tools.ietf.org/html/rfc7807

Installation

Install-Package ProblemNet

Configuration

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddProblemDetails(cfg => { cfg.DefaultTypeBaseUri = "https://sample.com/problemdetails/"; });

            services.AddMvc().
                     UseProblemDetailsInvalidModelStateResponseFactory();
    }

    public void Configure(IApplicationBuilder app)
    {
        app.UseProblemDetailsExceptionHandler();
        ..
        ..
        ...
    }
}

Usage

Creating Problems

There are different ways to create problems.

• Simple

   throw new ProblemDetailsException()
                    {
                            Type = "user-not-exists",
                            Title = "User Not Exists",
                            Status = (int)HttpStatusCode.NotFound,
                            Detail = "Users cannot be found"
                    };

  Will produce this response

    "type": "https://userservice.com/problemdetails/user-not-exists",
    "title": "User Not Exists",
    "status": 404,
    "detail": "Users cannot be found",
    "instance": "/api/Samples/problem-details-simple"

• Additional Members

   throw new ProblemDetailsException
                    {
                            Status = (int)HttpStatusCode.NotFound,
                            Title = $"Users cannot be found",
                            Extensions =
                            {
                                    new KeyValuePair<string, object>("Order", new { OrderId = 1, OrderDate = DateTime.UtcNow, Status = "Approved" }),
                                    new KeyValuePair<string, object>("UserId", 123)
                            }
                    };

  Will produce this

   "type": "https://userservice.com/problemdetails/",
   "title": "Users cannot be found",
   "status": 404,
   "instance": "/api/Samples/problem-details-additional-members",
   "order": {
     "orderId": 1,
     "orderDate": "2019-09-07T14:24:45.1783264Z",
     "status": "Approved"
   },
   "userId": 123

• Custom Validation Exception

  var validationProblems = new List<ValidationProblem>
                                       {
                                               new ValidationProblem("FirstName", "FirstName length must be less than 50 characters", "FirstName should only contain letters"),
                                               new ValidationProblem("Email", "Email address length must be greater than 5 characters", "Email address must be email format")
                                       };
  throw new ValidationProblemDetailsException(validationProblems.ToArray())
                    {
                            Detail = "Error while creating account. Please see errors for detail.",
                            Status = (int)HttpStatusCode.BadRequest,
                            Title = "Register Error"
                    };
              

  Will produce this

    ```

• Exceptions Except Problem Details

  throw new NullReferenceException();

  Will produce the following output. If the environment is development, the content of the exception property will not be empty.

   "exception": {  },
   "type": "https://httpstatuses.com/500",
   "title": "Internal Server Error",
   "status": 500,
   "detail": "An error occurred while processing your request",
   "instance": "/api/Samples/unhandled-exception"
    ```

Response Headers

The same http response headers will be produced regardless of exception type on the lines below. Middleware also ensures that problem responses never cached.

   cache-control: no-cache, no-store, must-revalidate 
   content-type: application/problem+json; charset=utf-8 
   date: Sat, 07 Sep 2019 14:03:55 GMT 
   expires: 0 
   pragma: no-cache 
   server: Kestrel 
   transfer-encoding: chunked