我有一个使用WCF Rest客户端生成的简单JSON,但是当我尝试反序列化响应时,我在JSON.Net中遇到了NullReferenceException
错误。我有以下JSON:
{"Code":-2146232800,"ExceptionType":"IOException","Message":"Msg","Stacktrace":"Some"}
以下是相关的类:
[DataContract]
public class FileUploadError
{
public FileUploadError(Exception exception)
{
Code = exception.HResult;
ExceptionType = exception.GetType().Name;
Message = GetMessage(exception);
Stacktrace = exception.StackTrace;
if (exception.Data.Count > 0)
{
Data = string.Join(Environment.NewLine, exception.Data.Cast<DictionaryEntry>().Select(x => x.Key + "=" + x.Value));
}
}
private string GetMessage(Exception exception)
{
if (exception.InnerException == null)
{
return exception.Message;
}
const string delimiter = "->";
var sb = new StringBuilder(1024);
for (var ex = exception; ex != null; ex = ex.InnerException)
{
sb.Append(ex.Message).Append(delimiter);
}
sb.Length -= delimiter.Length;
return sb.ToString();
}
[DataMember(IsRequired = true)]
[JsonProperty("Code", NullValueHandling = NullValueHandling.Ignore)]
public int Code { get; set; }
[DataMember(IsRequired = true)]
[JsonProperty("ExceptionType", NullValueHandling = NullValueHandling.Ignore)]
public string ExceptionType { get; set; }
[DataMember(EmitDefaultValue = false)]
[JsonProperty("Message", NullValueHandling = NullValueHandling.Ignore)]
public string Message { get; set; }
[DataMember(EmitDefaultValue = false)]
[JsonProperty("Stacktrace", NullValueHandling = NullValueHandling.Ignore)]
public string Stacktrace { get; set; }
[DataMember(EmitDefaultValue = false)]
[JsonProperty("Data", NullValueHandling = NullValueHandling.Ignore)]
public string Data { get; set; }
}
然后我对其进行反序列化:
const string text = "{\"Code\":-2146232800,\"ExceptionType\":\"IOException\",\"Message\":\"Msg\",\"Stacktrace\":\"Some\"}";
var obj = JsonConvert.DeserializeObject<FileUploadError>(text);
出现了子对象错误。如果需要,我可以提供在新的控制台应用程序中重现该错误的示例。
JSON非常简单,为什么会出现这个错误?
示例:https://dotnetfiddle.net/76FJd0
堆栈跟踪:
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at FileUploadError..ctor(Exception exception) in d:\Windows\Temp\nclgvim3.0.cs:line 28
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.ConstructorInfo.Invoke(Object[] parameters)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObjectFromNonDefaultConstructor(JsonReader reader, JsonObjectContract contract, JsonProperty containerProperty, ConstructorInfo constructorInfo, String id)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)
at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings)
at Program.Main(String[] args)
exception.HResult
会抛出异常,因为你的exception
参数是null
。既然你没有问“为什么我的异常参数是 null”,那么这个问题就是一个重复的问题。 - Lasse V. KarlsenNullReferenceException
,它并没有提供任何信息。答案应该首先提供解决这个问题的方法。 - jeromej