XML和JSON结果显示了WEB API中常见类的不同结果

Question

在我的WEB中，我得到了XML和Json的结果。效果很好。但是，当我从DB收集数据时，有些记录是空的。当转换到xml或json时，结果是不同的。用于输出的公共类是。

public  class items
{
    [JsonProperty(PropertyName = "frequency")]
    [XmlElement(ElementName = "frequency")]
    public string Frequency { get; set; }
    [JsonProperty(PropertyName = "modulation")]
    [XmlElement(ElementName = "modulation")]
    public string Modulation { get; set; }
}

转换发生在

var Station = new items
{
    Frequency = (mContent["frequency"] is DBNull) ? null : mContent["frequency"].ToString(),
    Modulation = (mContent["modulation"] is DBNull) ? null : mContent["modulation"].ToString(),
}

对于Json的结果，我得到了我真正想要的：

[{"items":[{"frequency":null,"modulation":null}]}]

XML显示

<items>
  <item/>
</items>

但我想

 <items>
  <item>
    <frequency/>
    <modulation/>
 </item>
</items>

怎么能这么做？

Answer 1

我认为您可能希望使用XmlElementAttribute.IsNullable属性：

public  class items
{
    [JsonProperty(PropertyName = "frequency")]
    [XmlElement(ElementName = "frequency", IsNullable = true)]
    public string Frequency { get; set; }
    [JsonProperty(PropertyName = "modulation")]
    [XmlElement(ElementName = "modulation", IsNullable = true)]
    public string Modulation { get; set; }
}

然后你应该得到：

<items>
  <item>
    <frequency xsi:nil = "true" />
    <modulation xsi:nil = "true" />
 </item>
</items>