“Type”属性的DataContract序列化

Question

如何在我的 DataContract 属性类中有效地序列化类型为“Type”的属性？我假设 Type 是一个不可序列化的类型（哇，这听起来很愚蠢。）我确信有一种方法可以满足我的需求。基本上我需要序列化一个类型的名称，以便工厂方法有效地构造，但我不想将它公开为字符串，我想要一个类型。

我知道有很多方法可以做到这一点，我很好奇目前还知道哪些其他方法。

编辑： 我刚刚意识到这可能是其他原因造成的，但这是错误，下面我有类定义。

不应使用数据合同名称“RuntimeType:http://schemas.datacontract.org/2004/07/System”键入“System.RuntimeType”。考虑使用 DataContractResolver 或将任何静态未知的类型添加到已知类型列表中 - 例如，通过使用 KnownTypeAttribute 属性或将它们添加到传递给 DataContractSerializer 的已知类型列表中。

[DataContract]
public class PlottingDeviceInfo : ObservableObject
{
    private string _deviceName;
    [DataMember]
    public string DeviceName
    {
        get
        {
            return _deviceName;
        }
        set
        {
            Set(() => DeviceName, ref _deviceName, value);
        }
    }

    private Type _deviceType;
    [DataMember]
    public Type DeviceType
    {
        get
        {
            return _deviceType;
        }
        set
        {
            Set(() => DeviceType, ref _deviceType, value);
        }
    }

    private DeviceSettingsInfo _settings;
    [DataMember]
    public DeviceSettingsInfo Settings
    {
        get
        {
            return _settings;
        }
        set
        {
            Set(() => Settings, ref _settings, value);
        }
    }

    private DeviceChannelInfo _channel;
    [DataMember]
    public DeviceChannelInfo Channel
    {
        get
        {
            return _channel;
        }
        set
        {
            Set(() => Channel, ref _channel, value);
        }
    }

    private DeviceCategory _deviceCategory;
    [IgnoreDataMember]
    public DeviceCategory DeviceCategory
    {
        get
        {
            return _deviceCategory;
        }
        set
        {
            Set(() => DeviceCategory, ref _deviceCategory, value);
        }
    }
}

这里是基类，用于增加 viewmodel 消费的可观察性。

[DataContract]
public class ObservableObject : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    [IgnoreDataMember]
    protected PropertyChangedEventHandler PropertyChangedHandler
    {
        get
        {
            return PropertyChanged;
        }
    }

    [Conditional("DEBUG")]
    [DebuggerStepThrough]
    public void VerifyPropertyName(string propertyName)
    {
        var myType = this.GetType();
        if (!string.IsNullOrEmpty(propertyName)
            && myType.GetProperty(propertyName) == null)
        {
            throw new ArgumentException("Property not found", propertyName);
        }
    }

    protected virtual void RaisePropertyChanged(string propertyName)
    {
        VerifyPropertyName(propertyName);

        var handler = PropertyChanged;

        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    protected virtual void RaisePropertyChanged<T>(Expression<Func<T>> propertyExpression)
    {
        if (propertyExpression == null)
        {
            return;
        }

        var handler = PropertyChanged;

        if (handler != null)
        {
            var body = propertyExpression.Body as MemberExpression;
            handler(this, new PropertyChangedEventArgs(body.Member.Name));
        }
    }

    protected void Set<T>(
        Expression<Func<T>> propertyExpression,
        ref T field,
        T newValue)
    {
        if (EqualityComparer<T>.Default.Equals(field, newValue))
        {
            return;
        }

        field = newValue;
        RaisePropertyChanged(propertyExpression);
    }

    protected void Set<T>(
        string propertyName,
        ref T field,
        T newValue)
    {
        if (EqualityComparer<T>.Default.Equals(field, newValue))
        {
            return;
        }

        field = newValue;
        RaisePropertyChanged(propertyName);
    }
}

Answer 1

Type 不能用跨平台的方式表示，所以它没有内置的表示。你最好的办法是将它表示为一个字符串，即

public Type DeviceType { get; set; }
[DataMember(Name="DeviceType")]
private string DeviceTypeName {
    get { return DeviceType == null ? null : DeviceType.AssemblyQualifiedName; }
    set { DeviceType = value == null ? null : Type.GetType(value); }
}

Answer 2

在根类中添加KnownType 属性，并将System.RuntimeType 作为类型传入。

在 C# 中，

[KnownType(typeof(System.RuntimeType))]

Answer 3

您还可以做的，特别是如果您不想更改PlottingDeviceInfo，是在DataContractSerializer 的构造函数中传递一个IDataContractSurrogate。我所做的（不知道是否有更简单的方法）是定义

public class TypeWrapper
{
    public string TypeName;
}

然后像这样使用它：

public class TypeReplacementSurrogate : IDataContractSurrogate
{
    public object GetCustomDataToExport(Type clrType, Type dataContractType)
    {
        return null;
    }

    public object GetCustomDataToExport(MemberInfo memberInfo, Type dataContractType)
    {
        return null;
    }

    public Type GetDataContractType(Type type)
    {
        if(type == typeof(Type))
        {
            return typeof (TypeWrapper);
        }

        return type;
    }

    public object GetDeserializedObject(object obj, Type targetType)
    {
        var objAsTypeWrapper = obj as TypeWrapper;
        if (objAsTypeWrapper != null)
        {
            return Assembly.GetExecutingAssembly().GetType(objAsTypeWrapper.TypeName);
        }

        return obj;
    }


    public void GetKnownCustomDataTypes(System.Collections.ObjectModel.Collection<Type> customDataTypes)
    {
    }

    public object GetObjectToSerialize(object obj, Type targetType)
    {
        var objAsType = obj as Type;
        if (objAsType != null)
        {
            return new TypeWrapper() {TypeName = objAsType.FullName};
        }

        return obj;
    }

    public Type GetReferencedTypeOnImport(string typeName, string typeNamespace, object customData)
    {
        return null;
    }

    public System.CodeDom.CodeTypeDeclaration ProcessImportedType(
        System.CodeDom.CodeTypeDeclaration typeDeclaration, System.CodeDom.CodeCompileUnit compileUnit)
    {
        return null;
    }
}