c# - 通过Json Formatter引发异常时，如何在ASP.NET Web Api中全局处理异常

Question

我们使用WebApi2和AngularJs开发ASP.NET MVC5应用程序。对于序列化和反序列化，我们使用custum JsonNetFormatter，如下所示:

public class JsonNetFormatter : MediaTypeFormatter
{

    //  other codes for formatting

    public override Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext)
    {
        string NameOfSet = "";
        ObjectWrapperWithNameOfSet obj = value as ObjectWrapperWithNameOfSet;
        if (obj != null)
        {
            NameOfSet = obj.NameOfSet;
            value = obj.WrappedObject;
        }

        _jsonSerializerSettings.ContractResolver = new CustomContractResolver(NameOfSet);

        // Create a serializer
        JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);

        // Create task writing the serialized content
        return Task.Factory.StartNew(() =>
        {
            using (JsonTextWriter jsonTextWriter = new JsonTextWriter(new StreamWriter(writeStream, SupportedEncodings[0])) { CloseOutput = false })
            {
                serializer.Serialize(jsonTextWriter, value);
                jsonTextWriter.Flush();
            }
        });
    }
}

和WebApiConfig如下:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        // Web API configuration and services

        // Web API routes

        config.Formatters.Clear();
        config.Formatters.Insert(0, new JsonNetFormatter());
    }
}

该应用程序工作正常。但是在某些情况下，反序列化json数据时会出错。我的问题是我们如何处理这些错误并发送给客户端？

错误示例:

Answer 1

您可以创建自己的自定义异常处理程序，以在将其发送到客户端之前修改所有错误消息。

    public class ErrorHandler : ExceptionHandler
    {
        public override void Handle(ExceptionHandlerContext context)
        {

            context.Result = new TextPlainErrorResult()
            {
                Request = context.ExceptionContext.Request,
                Content = "Oops! Sorry! Something went wrong." + "Please contact support so we can try to fix it."
            };
        }

        private class TextPlainErrorResult : IHttpActionResult
        {
            public HttpRequestMessage Request { get; set; }

            public string Content { get; set; }

            public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken)
            {
                HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.InternalServerError, Content);
                return Task.FromResult(response);
            }
        }
    }

然后在配置类中注册此自定义类，如下所示
config.Services.Replace(typeof(IExceptionHandler), new ErrorHandler());