c# - 有条件地序列化/反序列化属性

Question

我有一个类，其对象必须根据 bool 值序列化/反序列化一个属性

[System.SerializableAttribute()]
public class Foo
{
    private string myField;
    private bool myFieldSerializes;

    //Parameterless construction for serializing purposes
    public Foo() { }

    public Foo(string myField, bool myFieldSerializes)
    {
        this.myField = myField;
        this.myFieldSerializes = myFieldSerializes;
    }

    public string MyField
    {
        get {return this.myField;}
        set {this.myField = value;}
    }

    [System.Xml.Serialization.XmlIgnoreAttribute()]
    public bool MyFieldSerializes
    {
        get {return this.myFieldSerialzes;}
        set {this.myFieldSerialzes = value;}
    }
}

它应该是这样工作的:

• 如果我创建一个实例并将 myFieldSerializes 设置为“true”，则在序列化对象(使用 XMLSerialize)时，必须序列化 myField(包含在 XML 消息中)。如果设置为“false”，则应将其忽略。

• 反序列化(使用 XMLDeserialize)时， bool 值 myFieldSerializes 应该告诉我 myField 是否已被反序列化(换句话说，它存在于 XML 文件中)。

实现这种行为的方式是什么？

谢谢! :)

Answer 1

您的要求与XmlSerializer 的propertyNameSpecified 模式相匹配。来自docs :

If a schema includes an element that is optional ... [one] option is to use a special pattern to create a Boolean field recognized by the XmlSerializer, and to apply the XmlIgnoreAttribute to the field. The pattern is created in the form of propertyNameSpecified. For example, if there is a field named "MyFirstName" you would also create a field named "MyFirstNameSpecified" that instructs the XmlSerializer whether to generate the XML element named "MyFirstName".

此模式的便利之处在于，除了记录的行为之外，在反序列化过程中，如果遇到属性，XmlSerializer 会将 propertyNameSpecified 设置为 true -- 这正是你需要什么。因此你的类应该是这样的:

public class Foo
{
    private string myField;
    private bool myFieldSerializes;

    //Parameterless construction for serializing purposes
    public Foo() { }

    public Foo(string myField, bool myFieldSerializes)
    {
        this.myField = myField;
        this.myFieldSerializes = myFieldSerializes;
    }

    [XmlElement(IsNullable = true)] // Emit a value even when null as long as MyFieldSpecified == true
    public string MyField
    {
        get { return this.myField; }
        set { this.myField = value; }
    }

    [System.Xml.Serialization.XmlIgnoreAttribute()]
    public bool MyFieldSpecified { get { return myFieldSerializes; } set { myFieldSerializes = value; } }
}

(将 [XmlElement(IsNullable = true)] 添加到您的 MyField 属性可确保当 MyFieldSpecified == true，即使该字段本身为 null。)

原型(prototype) fiddle .