c# - XML 将空属性反序列化为零和假

Question

我正在将缺少某些属性的 xml 文档传递给反序列化器。我需要结果对象中的缺失值为 null，但目前 ints 反序列化为零，bools 为 false。

下面的示例显示了一个正确反序列化了 vals 的文档，但是没有 vals 的文档返回了零和空值。

如何强制反序列化器不这样处理缺失的属性。

using System;
using System.IO;
using System.Xml;
using System.Xml.Serialization;

namespace SOQuestion
{
    class Program
    {
        static void Main(string[] args)
        {

            var resultWithVals = getObject(docWithVals());
            var resultWithoutVals = getObject(docWithoutVals());

            Console.WriteLine("WITH VALS");
            Console.WriteLine(resultWithVals.someBool);
            Console.WriteLine(resultWithVals.someFloat);
            Console.WriteLine(resultWithVals.someInt);
            Console.WriteLine(resultWithVals.someString);


            Console.WriteLine("WITHOUT VALS"); // nulls are returned here as zero and false
            Console.WriteLine(resultWithoutVals.someBool);
            Console.WriteLine(resultWithoutVals.someFloat);
            Console.WriteLine(resultWithoutVals.someInt);
            Console.WriteLine(resultWithoutVals.someString);

            Console.ReadLine();


        }

        public static XmlDocument docWithVals()
        {
            var doc = new XmlDocument();
            var el = (XmlElement)doc.AppendChild(doc.CreateElement("Result"));
            el.SetAttribute("someString", "Hello World");
            el.SetAttribute("someBool", "true");
            el.SetAttribute("someInt", "1");
            el.SetAttribute("someFloat", "1.1");
            return doc;

        }

        public static XmlDocument docWithoutVals()
        {
            var doc = new XmlDocument();
            var el = (XmlElement)doc.AppendChild(doc.CreateElement("Result"));
            el.SetAttribute("someString", "Hello World");
            return doc;

        }


        public static Result getObject(XmlDocument doc)
        {

                var mySerializer = new XmlSerializer(new Result().GetType());
                var myStream = new MemoryStream();
                doc.Save(myStream);
                myStream.Position = 0;
                var r = mySerializer.Deserialize(myStream);
                return (Result)r;
         }

    }

    [Serializable]
    public class Result
    {
        [XmlAttribute]
        public string someString { get; set; }
        [XmlAttribute]
        public bool someBool { get; set; }
        [XmlAttribute]
        public int someInt { get; set; }
        [XmlAttribute]
        public float someFloat { get; set; }

    }

}

Answer 1

您可以使用 DefaultValueAttribute 为未初始化的字段提供默认值。在你的情况下你可以写

using System.ComponentModel;
using System.Configuration;

[XmlAttribute, DefaultValue(true)]
public bool someBool { get; set; }

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编辑。请参阅 MSND 页面上的说明 note on MSDN :

A DefaultValueAttribute will not cause a member to be automatically initialized with the attribute's value. You must set the initial value in your code.

此问题也已在 XML serialization and DefaultValue("") related problem in c# 中解决. 因此，要设置默认值，您必须在代码中指定这些值。

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希望对您有所帮助。