Intercept webapi json formatting errors

问题

I'd like to have a way to intercept the exception that occurs when you send in malformed json to a webapi endpoint, so that I can return a semantic error code as opposed to just 500. (e.g. "Fix your broken JSON or go to hell")

回答1:

You can create your custom validation filter attribute by deriving from ActionFilterAttribute:

public class ValidationFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        if (!actionContext.ModelState.IsValid)
        {
            actionContext.Response = actionContext
                                     .Request
                                     .CreateErrorResponse(HttpStatusCode.BadRequest,
                                                          actionContext.ModelState);
        }
    }
}

Now, you may either decorate your actions with it:

[HttpGet]
[ValidationFilter()]
public string DoSomethingCool()

or register it globally via your config:

config.Filters.Add(new ValidationFilterAttribute());

来源：https://stackoverflow.com/questions/26424404/intercept-webapi-json-formatting-errors