General error handling

#1

Hi all!
I would like to know which is the best way to handle a general, app-level error system; I find myself to reuse this code for each error response:

            var responseDto = new ErrorResponse
            {
                ResponseStatus = new ResponseStatus
                {
                    ErrorCode = "my error code",
                    Message = "my response message"
                }
            };

            return new HttpError(HttpStatusCode.NotFound, "Not Found")
            {
                Response = responseDto
            };

Should I put it in a class and recall it from each service? Should I write an Interface system like the LogManager does?
Thank you!

#2

For returning a 404 I’ll just:

throw HttpError.NotFound("User does not exist");
#3

Hi mythz, yes… I know I can use it… but if I don’t specify the responseDto it reports me something like:

{"ResponseStatus":{"ErrorCode":"Not Found","Message":"Not Found","Errors":[]}}

I would to have more control on this output so I’m using this:

            var responseDto = new ErrorResponse
            {
                ResponseStatus = new ResponseStatus
                {
                    ErrorCode = "my error code",
                    Message = "my response message"
                }
            };

            return new HttpError(HttpStatusCode.NotFound, "Not Found")
            {
                Response = responseDto
            };

I would like to know which is the best way to reuse this code in my project.

#4

It also more importantly populates the HTTP Response Status and description which is most of the time the only thing HTTP clients need to look at. They know a 404 means that what they requested doesn’t exist and can handle it in the most appropriate way for their app.

As for DRY code, treat it just like any other C# code you want to reuse. There’s nothing special about ServiceStack classes, refactor out the common parts into a method just as you would normally, my pref is to use readable extension methods, but use whatever you’re comfortable with.

#5

I’m generally a newbie with C# code design… the solution I found is to declare for each service a new custom class that handle error responses:

private static CustomError responder = new CustomError();

Than I call the methods where I need like this:

responder.NotFound("my cusom message");

Could be a performance problem reinitialize the class for each service?

#6

No it wont have any noticeable impact on performance. Also a static instance is only ever initialized once, however I don’t see any benefit of having a private static instance per class vs just calling a static method:

CustomError.NotFound("my custom message");

But it’s not going to be noticeable either way, although I’d always recommend the least code option where available.

#7

Yes mythz, you’re definitely right… I realized it just after I posted the comment!
I will use your solution for sure.

Thank you!