离开应用程序时无法序列化类型“System.Windows.UIElement”

Question

我遇到了这种情况：

Custom Control -> Navigate to its Settings Page -> Tap on a button in the Settings Page -> Show a PhotoChooserTask

所以，假设这个自定义控件必须只显示从用户库加载的图像。

点击用户控件时，我会显示一个 XAML 设置页面，其中有一个用于从图库加载图像的按钮，此按钮启动 PhotoChooserTask。

现在，问题是它在启动任务后立即引发异常。

这是堆栈跟踪：

    +       $exception  {System.Runtime.Serialization.InvalidDataContractException: Type 'System.Windows.UIElement' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. Alternatively, you can ensure that the type is public and has a parameterless constructor - all public members of the type will then be serialized, and no attributes will be required.
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.ThrowInvalidDataContractException(String message, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper..ctor(Type type)
   at System.Runtime.Serialization.ClassDataContract..ctor(Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper..ctor(Type type)
   at System.Runtime.Serialization.ClassDataContract..ctor(Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper..ctor(Type type)
   at System.Runtime.Serialization.ClassDataContract..ctor(Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper..ctor(Type type)
   at System.Runtime.Serialization.ClassDataContract..ctor(Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper..ctor(Type type)
   at System.Runtime.Serialization.ClassDataContract..ctor(Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper..ctor(Type type)
   at System.Runtime.Serialization.ClassDataContract..ctor(Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.ClassDataContract.ClassDataContractCriticalHelper..ctor(Type type)
   at System.Runtime.Serialization.ClassDataContract..ctor(Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
   at System.Runtime.Serialization.XmlObjectSerializerContext.GetDataContract(RuntimeTypeHandle typeHandle, Type type)
   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiType(XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle objectTypeHandle, Type objectType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, Type declaredType)
   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle)
   at WriteKeyValueOfstringanyTypeToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , ClassDataContract )
   at System.Runtime.Serialization.ClassDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context)
   at WriteArrayOfKeyValueOfstringanyTypeToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , CollectionDataContract )
   at System.Runtime.Serialization.CollectionDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context)
   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle)
   at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithoutXsiType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle)
   at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.XmlObjectSerializer.WriteObject(XmlDictionaryWriter writer, Object graph)
   at System.Runtime.Serialization.XmlObjectSerializer.WriteObject(Stream stream, Object graph)
   at Microsoft.Phone.Shell.BaseStreamPersister.Serialize(IDictionary`2 dictionary, IEnumerable`1 knownTypes)
   at Microsoft.Phone.Shell.PhoneApplicationService.SaveState()
   at Microsoft.Phone.Shell.PhoneApplicationService.FireDeactivated(UInt32 reason)
   at Microsoft.Phone.TaskModel.Interop.ITask.Pause.Invoke(UInt32 reason)
   at Microsoft.Phone.TaskModel.Interop.Task.FireOnPause(UInt32 reason)}    System.Exception {System.Runtime.Serialization.InvalidDataContractException}

我知道这与应用程序的状态完全相关，我认为这是因为操作系统试图“冻结”应用程序以在任务完成后恢复其状态。

我不明白这个系统是如何工作的，以及我必须做些什么来避免异常并使其正确序列化我的组件。

请记住，我有多个继承级别（类似于 `UserControl -> Custom 1 -> Custom 2 -> Custom 3 -> Current Custom Control）。

有什么想法吗？

编辑：

经过一些实验，我发现每次我离开应用程序时都会抛出异常，但前提是我在设置页面中。

不管我是通过启动任务还是点击窗口按钮离开它。

现在，这是我使用外部库（Coding4Fun Toolkit）的唯一页面，所以我猜这是问题所在，但我仍然不知道如何修复它，或者这是库的错误！

Answer 1

这个InvalidDataContractException被抛出

DataContractSerializer 或 NetDataContractSerializer 在序列化和反序列化期间遇到无效的数据协定。 （来自 MSDN）

如果您试图在您的应用程序中围绕UserControl 区域进行序列化，那么您没有正确实现序列化...这可以修复。

但是，如果您的应用程序中没有序列化或反序列化代码，则此序列化正在由您添加到应用程序的控件或类似物执行... 此 为真，那么你有一个更大的问题，因为你可能无法访问代码来解决问题。

参考您的评论“因为异常的消息建议我这样做”，您是否使用序列化之前你得到这个Exception？