Activities of "kaixin"

when I Update [User] Object, and return this object. then get an error : Response Body:

{
  "message": "An error has occurred.",
  "exceptionMessage": "The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.",
  "exceptionType": "System.InvalidOperationException",
  "stackTrace": null,
  "innerException": {
    "message": "An error has occurred.",
    "exceptionMessage": "Error getting value from 'CreatorUser' on 'System.Data.Entity.DynamicProxies.User_698FBAB5DA826A8924500EC1DF1F8FCC3CE3D42EFDADDFE0CFF03329EDF43ADD'.",
    "exceptionType": "Newtonsoft.Json.JsonSerializationException",
    "stackTrace": "   在 Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)\r\n   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue)\r\n   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)\r\n   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)\r\n   在 Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)\r\n   在 Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)\r\n   在 System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding)\r\n   在 System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, Encoding effectiveEncoding)\r\n   在 System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content)\r\n   在 System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken)\r\n--- 引发异常的上一位置中堆栈跟踪的末尾 ---\r\n   在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   在 System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__1b.MoveNext()",
    "innerException": {
      "message": "An error has occurred.",
      "exceptionMessage": "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.",
      "exceptionType": "System.ObjectDisposedException",
      "stackTrace": "   在 System.Data.Entity.Core.Objects.ObjectContext.get_Connection()\r\n   在 System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)\r\n   在 System.Data.Entity.Core.Objects.ObjectQuery`1.Execute(MergeOption mergeOption)\r\n   在 System.Data.Entity.Core.Objects.DataClasses.EntityReference`1.Load(MergeOption mergeOption)\r\n   在 System.Data.Entity.Core.Objects.DataClasses.RelatedEnd.DeferredLoad()\r\n   在 System.Data.Entity.Core.Objects.Internal.LazyLoadBehavior.LoadProperty[TItem](TItem propertyValue, String relationshipName, String targetRoleName, Boolean mustBeNull, Object wrapperObject)\r\n   在 System.Data.Entity.Core.Objects.Internal.LazyLoadBehavior.&lt;&gt;c__DisplayClass7`2.<GetInterceptorDelegate>b__2(TProxy proxy, TItem item)\r\n   在 System.Data.Entity.DynamicProxies.User_698FBAB5DA826A8924500EC1DF1F8FCC3CE3D42EFDADDFE0CFF03329EDF43ADD.get_CreatorUser()\r\n   在 GetCreatorUser(Object )\r\n   在 Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)"
    }
  }
}

Response Code : 500

Response Headers:

{
  "date": "Sun, 31 Jul 2016 18:24:19 GMT",
  "server": "Microsoft-IIS/10.0",
  "x-aspnet-version": "4.0.30319",
  "x-powered-by": "ASP.NET",
  "content-type": "application/json; charset=utf-8",
  "cache-control": "private",
  "x-sourcefiles": "=?UTF-8?B?RDpcUHJvamVjdFxkb25ldF9wcm9qZWN0XFZNRVMwMVxWTUVTLldlYlxhcGlcc2VydmljZXNcYXBwXHVzZXJcVXBkYXRlVXNlcg==?=",
  "content-length": "4390"
}

my source code:

public async Task<User> UpdateUser(long id, CreateUserInput input)
{
    var user = await _userRepository.GetAsync(id);

   
    if (input.Password != "password")
    {
        user.Password = new PasswordHasher().HashPassword(input.Password);
    }

   
    user.DisplayName = input.DisplayName;
    user.Mobile = input.Mobile;
    user.IsActive = input.IsActive;
    
    

    try
    {
        var result = (await _userRepository.UpdateAsync(user)).MapTo<User>();
        await CurrentUnitOfWork.SaveChangesAsync();
        return result;
    }
    catch (Exception err)
    {
        throw err;
    }
}