用空元素反序列化Xml [英] Deserialize Xml with empty elements

问题描述

考虑以下XML：

<a>
    <b>2</b>
    <c></c>
</a>  

我需要将此xml反序列化为对象。所以，我写了下面的课。

I need to deserialize this xml to an object. So, i wrote the following class.

public class A
{
    [XmlElement("b", Namespace = "")]
    public int? B { get; set; }

    [XmlElement("c", Namespace = "")]
    public int? C { get; set; }

}

由于我使用的是nullables，因此我一直期待着，当反序列化上述xml时，我将获得具有空C属性的对象A。

Since i'm using nullables, i was expecting that, when deserialing the above xml, i would get an object A with a null C property.

相反，我得到了一个异常，告诉文档有错误。 / p>

Instead of this, i get an exception telling the document has an error.

推荐答案

missing 元素和 null 元素之间存在区别。

There's a difference between a missing element and a null element.

缺少的元素< a< b> 2< / b< / a> 。这里C将使用 DefaultValue 属性采用您指定的任何默认值，如果没有显式的默认值，则为null。

A missing element, <a><b>2</b></a>. Here C would take whatever default value you specify, using the DefaultValue attribute, or null if there's no explicit default.

空元素 a a b 2 2 / b> c xs：Nil ='true'/< / a 。

当您执行< a< b> 2< / b< c>< / c>< a /> xml序列化程序将尝试解析字符串。如果为空，则它将正确地失败。

When you do <a><b>2</b><c></c><a/> the xml serializer will try to parse string.Empty as an integer an will correctly fail.

提供程序正在生成无效的xml，如果使用XmlSerializer，则需要执行以下操作：

Since your provider is generating invalid xml you will need to do this, if using the XmlSerializer:

[XmlRoot(ElementName = "a")]
public class A
{
    [XmlElement(ElementName = "b")]
    public int? B { get; set; }

    [XmlElement(ElementName = "c")]
    public string _c { get; set; }

    public int? C
    {
        get
        {
            int retval;

            return !string.IsNullOrWhiteSpace(_c) && int.TryParse(_c, out retval) ? (int?) retval : null;
        }
    }
}

或使用DataContractSerializer稍好

or slightly better using the DataContractSerializer

[DataContract(Name="a")]
public class A1
{
    [DataMember(Name = "b")]
    public int? B { get; set; }

    [DataMember(Name = "c")]
    private string _c { get; set; }

    public int? C
    {
        get
        {
            int retval;

            return !string.IsNullOrWhiteSpace(_c) && int.TryParse(_c, out retval) ? (int?)retval : null;
        }
    }
}

尽管DataContractSerializer不会支持属性（如果有问题的话）。

although the DataContractSerializer doesn't support attributes if that's a problem.

这篇关于用空元素反序列化Xml的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！