在类级别声明 [XmlElement(IsNullable = true)]

Question

有没有办法在类级别声明 [XmlElement(IsNullable = true)] 以便类中的所有属性都将被 XML 序列化，即使它们为 null？

例如

public BankAccount BankAccount { get;放; }

应该导致 ，而不是默认的缺失元素。

我尝试了这个，但编译器（正确地）指出该属性对于类声明无效。

这样做的原因是我不想为所有属性指定这一点。

---

编辑：这是我正在使用的序列化方法：

        var serializer = new XmlSerializer(FormType);
        var stream = new MemoryStream();

        serializer.Serialize(stream, form);

Answer 1

不幸的是，在为 XML 序列化类注释时必须明确。
每个属性都必须使用其自己的 XmlElement 属性进行注释，除非您想要默认行为。

Answer 2

请参阅此线程： 设置 [XmlElement(IsNullable = true)] 属性运行时间

Answer 3

你可以这样做，注意这仅涵盖简单的嵌套类

public class NestedClass
{
    public int MyNestedInt { get; set; }
    public int? MyNestedNullableInt { get; set; }
    public string MyNestedString { get; set; }
}

public class TestOverrideClass
{
    public int MyInt { get; set; }
    public int? MyNullableInt { get; set; }
    public string MyString { get; set; }
    public NestedClass NestedClass { get; set; } = new NestedClass();

    public static string TestOverride()
    {
        string output = TestOverride<TestOverrideClass>(new TestOverrideClass());
        return output;
    }

    public static string TestOverride<T>(object objectToSerialize)
    {
        StringBuilder output = new StringBuilder();

        // Create an XmlWriterSettings object with the correct options.
        XmlWriterSettings settings = new XmlWriterSettings();
        settings.Indent = true;
        settings.IndentChars = ("\t");
        settings.OmitXmlDeclaration = true;

        // Create the XmlWriter object and write some content.
        XmlWriter writer = null;
        writer = XmlWriter.Create(output, settings);
        var serializer = new XmlSerializer(typeof(T), GetNullOverrides<T>());
        serializer.Serialize(writer, objectToSerialize);

        return output.ToString();
    }

    private static XmlAttributeOverrides GetNullOverrides<T>()
    {
        // Create an XmlAttributes object with IsNullable set to true
        XmlAttributes attributes = new XmlAttributes();
        XmlElementAttribute attribute = new XmlElementAttribute { IsNullable = true };
        attributes.XmlElements.Add(attribute);

        // Create an XmlAttributeOverrides object
        XmlAttributeOverrides overrides = new XmlAttributeOverrides();

        AddOverRides(typeof(T), attributes, overrides);

        return overrides;
    }

    private static XmlAttributeOverrides AddOverRides(Type type, XmlAttributes attributes, XmlAttributeOverrides overrides)
    {
        // Apply the XmlAttributes to all properties T
        PropertyInfo[] properties = type.GetProperties();
        foreach (PropertyInfo property in properties)
        {
            if (!property.PropertyType.IsValueType)
                overrides.Add(type, property.Name, attributes);
            if (property.PropertyType.IsClass)
                AddOverRides(property.PropertyType, attributes, overrides);
        }
        return overrides;
    }
}