我可以在XSD C#生成的类创建的XML中的同一标签上具有null属性和其他属性吗?

XmlSerializer 不直接支持绑定到同时具有 xsi:nil ="true" 的元素以及其他属性值；请参见 Xsi​​:nil属性绑定支持:nil属性和其他属性.

XmlSerializer doesn't directly support binding to elements that simultaneously have xsi:nil="true" along with other attribute values; see Xsi:nil Attribute Binding Support: The nil attribute and other attributes.

因此，您需要手动发出该属性.

Thus, you need to emit the attribute manually.

如果您希望能够生成一个没有内容且具有两个属性的元素，一个名为 NV ，另一个始终为 xsi:nil ="true" ，则可以修改您的 testTag01 类，使其具有 NV 属性以及具有正确名称空间和名称的合成属性:

If you want to be able to generate an element with no content and two attributes, one named NV and the other always being xsi:nil="true", you can modify your testTag01 class to have the NV property as well as a synthetic property having the correct namespace and name:

public class testTag01 
{
    [XmlAttribute]
    public string NV { get; set; }

    [XmlAttribute("nil", Namespace = "http://www.w3.org/2001/XMLSchema-instance")]
    public string Nil { get { return "true"; } set { } }
}

如果您有时想要具有 xsi:nil ="true" ，但在其他时候希望元素具有与您的 SomeEnum 相对应的内容>，您需要做一些复杂的事情，因为当元素具有内容时，必须禁止 xsi:nil ="true" :

If you sometimes want to have xsi:nil="true" but at other times want the element to have content corresponding to your SomeEnum, you need to do something a bit more complicated, since the xsi:nil="true" must be suppressed when the element has content:

public class testTag01
{
    [XmlAttribute]
    public string NV { get; set; }

    [XmlAttribute("nil", Namespace = "http://www.w3.org/2001/XMLSchema-instance")]
    public string Nil { get { return SomeEnum == null ? "true" : null; } set { } }

    public bool ShouldSerializeNil() { return SomeEnum == null; }

    [XmlIgnore]
    public SomeEnum? SomeEnum { get; set; }

    [XmlText]
    public string SomeEnumText
    {
        get
        {
            if (SomeEnum == null)
                return null;
            return SomeEnum.Value.ToString();
        }
        set
        {
            // See here if one needs to parse XmlEnumAttribute attributes
            // http://stackoverflow.com/questions/3047125/retrieve-enum-value-based-on-xmlenumattribute-name-value
            value = value.Trim();
            if (string.IsNullOrEmpty(value))
                SomeEnum = null;
            else
            {
                try
                {
                    SomeEnum = (SomeEnum)Enum.Parse(typeof(SomeEnum), value, false);
                }
                catch (Exception)
                {
                    SomeEnum = (SomeEnum)Enum.Parse(typeof(SomeEnum), value, true);
                }
            }
        }
    }
}

(同时具有 xsi:nil ="true" 和内容的元素将违反

(An element that simultaneously has both xsi:nil="true" and content would be a violation of the XML standard; hopefully you don't have that.)

然后像这样使用它:

public class TestClass
{
    [XmlElement("testTag.01")]
    public testTag01 TestTag { get; set; }

    public static void Test()
    {
        Test(new TestClass { TestTag = new testTag01 { NV = "123123" } });
        Test(new TestClass { TestTag = new testTag01 { NV = "123123", SomeEnum = SomeEnum.SomeValue } });
    }

    private static void Test(TestClass test)
    {
        var xml = test.GetXml();

        var test2 = xml.LoadFromXML<TestClass>();

        Console.WriteLine(test2.GetXml());
        Debug.WriteLine(test2.GetXml());

        if (test2.TestTag.NV != test.TestTag.NV)
        {
            throw new InvalidOperationException("test2.TestTag.NV != test.TestTag.NV");
        }
    }
}

XML输出如下:

<TestClass xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <testTag.01 NV="123123" xsi:nil="true" />
</TestClass>

或

<TestClass xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <testTag.01 NV="123123">SomeValue</testTag.01>
</TestClass>

使用以下扩展方法制作原型小提琴:

Prototype fiddle using these extension methods:

public static class XmlSerializationHelper
{
    public static T LoadFromXML<T>(this string xmlString, XmlSerializer serializer = null)
    {
        T returnValue = default(T);

        using (StringReader reader = new StringReader(xmlString))
        {
            object result = (serializer ?? new XmlSerializer(typeof(T))).Deserialize(reader);
            if (result is T)
            {
                returnValue = (T)result;
            }
        }
        return returnValue;
    }

    public static string GetXml<T>(this T obj, XmlSerializerNamespaces ns = null, XmlWriterSettings settings = null, XmlSerializer serializer = null)
    {
        using (var textWriter = new StringWriter())
        {
            settings = settings ?? new XmlWriterSettings() { Indent = true, IndentChars = "  " }; // For cosmetic purposes.
            using (var xmlWriter = XmlWriter.Create(textWriter, settings))
                (serializer ?? new XmlSerializer(typeof(T))).Serialize(xmlWriter, obj, ns);
            return textWriter.ToString();
        }
    }
}