在反序列化期间使用XML装饰指定默认值 [英] Using XML decorations to specify default values during de-serialization

问题描述

我在反序列化某些XML时遇到问题；第三方提供的XML非常冗长，因此，如果没有为特定元素设置任何值，它将提供空白元素（例如< element1 /> ）。

I have a problem deserializing some XML; the XML supplied by a third party is quite verbose, so if there is no value set for an particular element, it will supply and empty element (e.g. <element1 />).

这对于某些元素（例如，用于存储整数的元素）是一个问题。我可以控制第三方，因此我可以让他们指定默认值（< myinteger> 0< / myinteger> ），也可以忽略它们这些元素完全。两者都应避免出现问题。

This is a problem for certain elements, for example, those that are meant to store integers. I have control over the third party, so I could either get them to specify a default value (<myinteger>0</myinteger>) or I can get them to omit these elements entirely. Both of these should avoid the problem.

但是，将来可能会出现一些情况，我们没有太多的控制权-在这种情况下，有没有办法

However, there may be situations in future, where we don't have so much control - in which case, is there a way of specifying, perhaps via a decoration, a default value?

    [XmlElement("myinteger")=0???]
    public int MyInteger
    {
        get
        {
            return myInteger;
        }
        set
        {
            myInteger= value;
        }
    }

推荐答案

XmlSerializer 确实支持 [DefaultValue] ，但它在序列化期间使用。在反序列化期间，它仅运行构造函数，然后获取传入的值并应用它们。因此，一种常见的方法是使用构造函数（或字段初始化器）：

XmlSerializer does support [DefaultValue], but it uses it during serialization. During deserialization, it simply runs the constructor, then takes incoming values and applies them. A common approach, then, is to use the constructor (or field-initializers):

public Foo() {
    Bar = 4;
}
[DefaultValue(4), XmlAttribute("bar")]
public int Bar {get;set;}

但是； XmlSerializer 对此的解释不是提供一个空元素，而是忽略该元素（/属性）。甚至 int？也不会映射为空。要处理 empty 元素，您必须将其作为字符串处理。这很丑。

However; XmlSerializer's interpretation of this is not "supply an empty element" - but rather "omit the element(/attribute)". Even int? doesn't map to "empty". To handle empty elements, you would have to handle it as a string. Which is ugly.

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