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禁止XmlSerializer发出空值类型

xml-serialization xml c#

Ben Griswold · 技术社区 · 17 年前

请考虑下面的金额值类型属性,该属性被标记为可空XMLNET:

[XmlElement(IsNullable=true)] 
public double? Amount { get ; set ; }

<amount xsi:nil="true" />

我希望XmlSerializer完全抑制该元素,而不是发出该元素。为什么?我们正在使用Authorize.NET进行在线支付,如果存在此空元素,Authorize.NET将拒绝请求。

当前的解决方案/解决方法是根本不序列化Amount value类型属性。相反,我们创建了一个互补属性SerializableMount,它基于Amount并被序列化。由于SerializableMount是String类型,与引用类型类似,如果默认为null,则XmlSerializer会抑制这些类型,因此一切都很正常。

/// <summary>
/// Gets or sets the amount.
/// </summary>
[XmlIgnore]
public double? Amount { get; set; }

/// <summary>
/// Gets or sets the amount for serialization purposes only.
/// This had to be done because setting value types to null 
/// does not prevent them from being included when a class 
/// is being serialized.  When a nullable value type is set 
/// to null, such as with the Amount property, the result 
/// looks like: &gt;amount xsi:nil="true" /&lt; which will 
/// cause the Authorize.NET to reject the request.  Strings 
/// when set to null will be removed as they are a 
/// reference type.
/// </summary>
[XmlElement("amount", IsNullable = false)]
public string SerializableAmount
{
    get { return this.Amount == null ? null : this.Amount.ToString(); }
    set { this.Amount = Convert.ToDouble(value); }
}

3 回复 | 直到 17 年前

137

Marc Gravell 17 年前

尝试添加:

public bool ShouldSerializeAmount() {
   return Amount != null;
}

框架的某些部分可以识别许多模式。欲知详情, XmlSerializer 也找 public bool AmountSpecified {get;set;} .

完整示例(也切换到 decimal ):

using System;
using System.Xml.Serialization;

public class Data {
    public decimal? Amount { get; set; }
    public bool ShouldSerializeAmount() {
        return Amount != null;
    }
    static void Main() {
        Data d = new Data();
        XmlSerializer ser = new XmlSerializer(d.GetType());
        ser.Serialize(Console.Out, d);
        Console.WriteLine();
        Console.WriteLine();
        d.Amount = 123.45M;
        ser.Serialize(Console.Out, d);
    }
}

更多有关 ShouldSerialize* on MSDN

mko 12 年前

还有另一种选择

 <amount /> instead of <amount xsi:nil="true" />

使用

[XmlElement("amount", IsNullable = false)]
public string SerializableAmount
{
    get { return this.Amount == null ? "" : this.Amount.ToString(); }
    set { this.Amount = Convert.ToDouble(value); }
}