将空XML元素反序列化为Guid.Empty-DeserializeemptyXMLelementasGuid.Empty

1  

The exception you are seeing explains the problem clearly:

您看到的例外情况清楚地解释了问题：

System.InvalidOperationException occurred
  Message="There is an error in XML document (3, 3)."
  InnerException: System.FormatException
       Message="Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)."

As stated, XmlSerializer does not support deserializing an empty string to a Guid. Thus you will need to do the conversion manually using a surrogate property:

如上所述，XmlSerializer不支持将空字符串反序列化为Guid。因此，您需要使用代理属性手动进行转换：

[XmlRoot("Order")]
public class Order
{
    [XmlIgnore]
    [JsonProperty("CardNumber")]
    public Guid? CardNumber { get; set; }

    [XmlElement(ElementName = "CardNumber", IsNullable = true)]
    [Browsable(false), EditorBrowsable(EditorBrowsableState.Never), DebuggerBrowsable(DebuggerBrowsableState.Never)]
    [JsonIgnore]
    public string XmlCardNumber
    {
        get
        {
            if (CardNumber == null)
                return null;
            else if (CardNumber.Value == Guid.Empty)
                return "";
            return XmlConvert.ToString(CardNumber.Value);
        }
        set
        {
            if (value == null)
                CardNumber = null;
            else if (string.IsNullOrEmpty(value))
                CardNumber = Guid.Empty;
            else
                CardNumber = XmlConvert.ToGuid(value);
        }
    }
}

If this is something you need to do in many different types that have Guid? properties, you can extract a surrogate type like so:

如果您需要在许多具有Guid的不同类型中执行此操作？属性，你可以提取代理类型，如下所示：

[XmlType(AnOnymousType= true, IncludeInSchema = false)]
public class XmlGuid
{
    [XmlIgnore]
    public Guid Guid { get; set; }

    [XmlText]
    public string XmlCardNumber
    {
        get
        {
            if (Guid == Guid.Empty)
                return null;
            return XmlConvert.ToString(Guid);
        }
        set
        {
            if (string.IsNullOrEmpty(value))
                Guid = Guid.Empty;
            else
                Guid = XmlConvert.ToGuid(value);
        }
    }

    public static implicit operator Guid?(XmlGuid x)
    {
        if (x == null)
            return null;
        return x.Guid;

    }

    public static implicit operator XmlGuid(Guid? g)
    {
        if (g == null)
            return null;
        return new XmlGuid { Guid = g.Value };
    }

    public static implicit operator Guid(XmlGuid x)
    {
        if (x == null)
            return Guid.Empty;
        return x.Guid;

    }

    public static implicit operator XmlGuid(Guid g)
    {
        return new XmlGuid { Guid = g };
    }
}

And use it like:

并使用它像：

[XmlRoot("Order")]
public class Order
{
    [XmlElement(Type = typeof(XmlGuid), ElementName = "CardNumber", IsNullable = true)]
    [JsonProperty("CardNumber")]
    public Guid? CardNumber { get; set; }
}

Here I am taking advantage of the fact that the XmlElementAttribute.Type property automatically picks up the implicit conversion I defined for Guid? from and to XmlGuid.

在这里，我利用了XmlElementAttribute.Type属性自动获取我为Guid定义的隐式转换这一事实？来自和到XmlGuid。

3  

Null is not the same as Guid.Empty. In the JSON serializer, you denote null using an empty string.

Null与Guid.Empty不同。在JSON序列化程序中，您使用空字符串表示null。

If you serialize your class using XmlSerializer you'll see it uses xsi:nil="true" to denote a null value.

如果使用XmlSerializer序列化类，您将看到它使用xsi：nil =“true”来表示空值。

For example:

例如：