c＃如何返回用户定义类型的空对象？

Question

I have a method that deserialize XML to Particular user defined type (Product Class).

public Class Product 
{
   public int ID{ get; set; }
   public string ModelNumber { get; set; }
   public string SKU { get; set; }
   public string Att4 { get; set; }
   public string Att5 { get; set; }
}

This Method will accept XML Object and read it's properties and return a product class. I have a condition when the XML is empty I want to return an empty object like this {}. Here is my deserialize method :

        public static Product DeserializeXmlAsParentProduct(object xml)
        {
            if (xml == DBNull.Value)
                return // I want to return {};
            var doc = XDocument.Parse(xml.ToString());
            var product = doc.Descendants("row").Select(pd => new Product
            {
                ID = GetValue<int>(pd.Element("ID")),
                ModelNumber = GetValue<string>(pd.Element("ModelNumber")),
                SKU = GetValue<string>(pd.Element("SKU"))
            })
            .ToList().FirstOrDefault();
            return product;
        }

My in put XML will look like this when a value is retrieved from the DB :

<root>
 <row>
  <ID>8</ID>
  <ModelNumber>GT</ModelNumber>
  <SKU>UR</SKU>
 <row/>
</root>

How Can I return empty object if the condition is met ?

Also If every thing went fine. It will return for me a product class with all the attributes.

{ID, ModelNumber, SKU, Att4, Att5}`

How can I use LINQ to return only the first three attributes only ? like this :

{ID, ModelNumber, SKU}

I was thinking of using dynamic object. Is there any Other way to achieve this?.

Any Help is appreciated.

Answer 1

Using Linq to construct anonymous instances:

var anonResults = list.Select( p => new {p.ID, p.ModelNumber, p.SKU });

However, in this example you cannot return anonResults . Anonymous classes are only valid in the scope in which they are first declared.

If you really want to do this dynamically, javascript style, I would use ExpandoObject

My recommendation is just return the full object. If you want to restrict access to Att4 and Att5 , consider implementing an interface on Product that only declares ID , ModelNumber and SKU :

public interface IProduct
{
    int ID{ get; set; }
    string ModelNumber { get; set; }
    string SKU { get; set; }
}

public Class Product : IProduct
{
   public int ID{ get; set; }
   public string ModelNumber { get; set; }
   public string SKU { get; set; }
   public string Att4 { get; set; }
   public string Att5 { get; set; }
}