我正在使用web api.我希望属性extractDate是一个属性.以下代码输出extractDate作为元素而不是属性

public Feed GetProducts()
    {
             var Feed = new Feed()
             {
                 extractDate = "extractDate",incremental = true,name = "name",Brands = GetBrands(),Categories = GetCategories(),Products = GetProducts()
             };


         return Feed;
    }

这是我的模型Feed.请注意,以下似乎不会将元素转换为属性

[XmlAttribute(AttributeName = "extractDate")]
public class Feed
{
    [XmlAttribute(AttributeName = "extractDate")] //attribute is ignored
    public string extractDate { get; set; }
    public bool incremental { get; set; }
    public string name { get; set; }
    public List<Brand> Brands { get; set; }
    public List<Category> Categories { get; set; } 
    public List<Product> Products { get; set; } 
}

我如何输出

<Feed extractDate="2012/01/01" 

// other logic

/>