为什么我反序列化时，总是提示system.argumentnullexception

[tanghuawei]

 protected override WorkflowCreationContext OnGetCreationContext(object[] inputs, OperationContext operationContext, Guid instanceId, WorkflowHostingResponseContext responseContext)
        {
            WorkflowCreationContext creationContext = new WorkflowCreationContext();

            if (operationContext.IncomingMessageHeaders.Action.EndsWith("StartWorkflow"))
            {
                IDictionary<string, object> arguments = (IDictionary<string, object>)inputs[1];

                if (arguments != null && arguments.Count > 0)
                {
                    foreach (KeyValuePair<string, object> pair in arguments)
                    {
                        if (pair.Value is DTOWrapper)
                        {
                            //这句执行Unwrap()时出错
                            creationContext.WorkflowArguments.Add(pair.Key, (pair.Value as DTOWrapper).Unwrap());
                        }
                        else
                            creationContext.WorkflowArguments.Add(pair.Key, pair.Value);
                    }
                }                
            }            
            else
            {
                new Logger(_connectionString)
                    .Log((Guid)inputs[0], "Invalid Action: " + operationContext.IncomingMessageHeaders.Action);
            }

            responseContext.SendResponse(null, null);

            return creationContext;
        }      

DTOWrapper类：

[Serializable]
    [DataContract]
    public class DTOWrapper
    {
        public DTOWrapper();
        public DTOWrapper(object obj);

        [DataMember]
        public string AssemblyName { get; set; }
        [DataMember]
        public string Data { get; set; }
        [DataMember]
        public string DataType { get; set; }

        public object Unwrap();
    }

异常信息：

System.ArgumentNullException was unhandled by user code
HResult=-2147467261
Message=Value cannot be null.
Parameter name: type
Source=System.Runtime.Serialization
ParamName=type
StackTrace:
at System.Runtime.Serialization.XmlObjectSerializer.CheckNull(Object obj, String name)
at System.Runtime.Serialization.DataContractSerializer.Initialize(Type type, IEnumerable`1 knownTypes, Int32 maxItemsInObjectGraph, Boolean ignoreExtensionDataObject, Boolean preserveObjectReferences, IDataContractSurrogate dataContractSurrogate, DataContractResolver dataContractResolver, Boolean serializeReadOnlyTypes)
at System.Runtime.Serialization.DataContractSerializer..ctor(Type type, IEnumerable`1 knownTypes, Int32 maxItemsInObjectGraph, Boolean ignoreExtensionDataObject, Boolean preserveObjectReferences, IDataContractSurrogate dataContractSurrogate, DataContractResolver dataContractResolver)
at System.Runtime.Serialization.DataContractSerializer..ctor(Type type, IEnumerable`1 knownTypes, Int32 maxItemsInObjectGraph, Boolean ignoreExtensionDataObject, Boolean preserveObjectReferences, IDataContractSurrogate dataContractSurrogate)
at System.Runtime.Serialization.DataContractSerializer..ctor(Type type, IEnumerable`1 knownTypes)
at System.Runtime.Serialization.DataContractSerializer..ctor(Type type)
at Achievo.ServiceManager.ServiceModel.DTOWrapper.Deserialize(Type t, String data)
at Achievo.ServiceManager.ServiceModel.DTOWrapper.Unwrap()
at Achievo.Workflow.Runtime.WorkflowRuntimeEndpoint.OnGetCreationContext(Object[] inputs, OperationContext operationContext, Guid instanceId, WorkflowHostingResponseContext responseContext)
at System.ServiceModel.Activities.Dispatcher.PersistenceContext.GetInstance(WorkflowGetInstanceContext parameters)
at System.ServiceModel.Activities.Dispatcher.DurableInstanceManager.GetInstanceAsyncResult.TryAcquire(Boolean fromCache)
at System.ServiceModel.Activities.Dispatcher.DurableInstanceManager.GetInstanceAsyncResult.HandleEndLoad(IAsyncResult result)
at System.Runtime.AsyncResult.AsyncCompletionWrapperCallback(IAsyncResult result)
InnerException:

[bdmh]

你先确认是那个对象为null

[tanghuawei]

我把xml打出来，貌似都有值

[tanghuawei]

这是Xml，需要转换为DonationRequestDto对象

<?xml version="1.0" encoding="utf-16"?>
<DonationRequestDto xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/Achievo.Service.WorkFlowForm.Contract">
	<CreatedBy i:nil="true" />
	<CreatedDate i:nil="true" />
	<UpdatedBy i:nil="true" />
	<UpdatedDate i:nil="true" />
	<AmountOfFunding>88</AmountOfFunding>
	<Applicant>Administrator</Applicant>
	<ApplicantId>2</ApplicantId>
	<ApproverIdSearch>0</ApproverIdSearch>
	<ApproverNameSearch i:nil="true" />
	<ApproverNames i:nil="true" />
	<ApprovingStatus i:nil="true" />
	<Assistant>Administrator</Assistant>
	<AssistantId>2</AssistantId>
	<AssoInfo i:nil="true" />
	<AuthorId>2</AuthorId>
	<Budgeted>false</Budgeted>
	<Category>General Donation</Category>
	<DD>dd</DD>
	<DateOfRequestorOrRecipientRequest>2014-04-28T00:00:00</DateOfRequestorOrRecipientRequest>
	<DescriptionOfHowFundWillBeUsed>ddd</DescriptionOfHowFundWillBeUsed>
	<DetailedDescriptionOfType>dd</DetailedDescriptionOfType>
	<DueDiligencePerformedDate>2014-04-28T16:37:45</DueDiligencePerformedDate>
	<EditingStatus>Draft</EditingStatus>
	<Explain>false</Explain>
	<ExplanationMakingProposedDonation>dd</ExplanationMakingProposedDonation>
	<FileDescription>dd</FileDescription>
	<FormName>Donation</FormName>
	<FromFormId i:nil="true" />
	<Id>275</Id>
	<IntValueOfEditingStatus>1</IntValueOfEditingStatus>
	<Nature>AdministratorGeneral DonationNature1</Nature>
	<NatureId>1</NatureId>
	<NextDueDiligenceReviewDate>2014-04-28T16:37:45</NextDueDiligenceReviewDate>
	<OwnerId>2</OwnerId>
	<PostEvent i:nil="true" />
	<ProductBrandIds xmlns:d2p1="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
		<d2p1:int>12</d2p1:int>
	</ProductBrandIds>
	<ProductBrandNames>EMLA brand</ProductBrandNames>
	<ProposeEndDateOfSupport>2014-04-28T00:00:00+08:00</ProposeEndDateOfSupport>
	<ProposeEndDateOfSupportFrom>0001-01-01T00:00:00</ProposeEndDateOfSupportFrom>
	<ProposeEndDateOfSupportTo>2014-04-30T00:00:00</ProposeEndDateOfSupportTo>
	<ProposeStartDateOfSupport>2014-04-28T00:00:00+08:00</ProposeStartDateOfSupport>
	<ProposeStartDateOfSupportFrom>0001-01-01T00:00:00</ProposeStartDateOfSupportFrom>
	<ProposeStartDateOfSupportTo>2014-04-28T00:00:00</ProposeStartDateOfSupportTo>
	<RecipientId>2</RecipientId>
	<RecipientName>ABM Hong Kong Swatow Baptist Church Community Service Association Limited, The</RecipientName>
	<Remarks>dd</Remarks>
	<RepresentationOrSuggestion i:nil="true" />
	<RequestNo>EG14000037</RequestNo>
	<RevisionNo i:nil="true" />
	<ShowStatusString i:nil="true" />
	<Sort i:nil="true" />
	<SortDir i:nil="true" />
	<SpecificIfOthers i:nil="true" />
	<Status i:nil="true" />
	<SubmitDate>2014-04-28T16:37:45.4628144+08:00</SubmitDate>
	<SubmitDateFrom>0001-01-01T00:00:00</SubmitDateFrom>
	<SubmitDateTo>0001-01-01T00:00:00</SubmitDateTo>
	<SupportingFileToAttach />
	<Urgent>Normal</Urgent>
	<UsedFundDescription i:nil="true" />
	<UserId>2</UserId>
	<WorkflowInstanceId>0</WorkflowInstanceId>
	<WorkflowName>Donation</WorkflowName>
	<WorkflowVersionId>41</WorkflowVersionId>
</DonationRequestDto>

[config_man]

pair.Value为null吧。 不过这种问题调试下不就知道了么？

[铜臂阿铁木]

<Status i:nil="true" /> 是enum？ 设计enum的时候要注意给设计个默认0值，否则可能出现类似问题。

[tanghuawei]

程序集的问题，跟这些没关系，谢谢各位