C# 从WCF服务器返回的对象为空

在客户机应用程序中，我输入了一个项目id，WCF服务器应该返回类型为

ItemDTO

的对象。但是，当作出答复时，对象是空的

ItemDTO itm = Connection.Instance.HttpProxy.GetItem(ItemID);

到目前为止，我可以证实的是：

• 已成功从数据库中获取请求的项目
• 映射确实有效（检查了结果映射的内容）
• 内容确实已发送（使用Fiddler检查）

• 但是，当我检查

  itm

  的内容时，它是空的

这是WCF服务器中的

GetItem（）

方法：

public ItemDTO GetItem(string itemID) {
    using (var db = new PoSEntities()) {
        var query = from i in db.Items
                    where i.ItemID.Equals(itemID)
                    select i;
        Item item = query.FirstOrDefault();
        return item == null ? null : Mapping.Map<Item, ItemDTO>(item);
    }
}

连接类别：

 public sealed class Connection {

    private readonly string _address = "http://Edwin:8080/PoS";
    private static Connection _instance;
    private static object _padLock = new Object();
    private static ChannelFactory<IPoS> httpFactory;

    private static IPoS _httpProxy; //Singleton
    public IPoS HttpProxy { get { return _httpProxy; } }

    public static Connection Instance {
        get {
            if (_instance == null) {
                lock (_padLock) {
                    if (_instance == null) {
                        _instance = new Connection();
                    }

                }
            }
            return _instance;
        }
    }

    private Connection() {
        httpFactory = new ChannelFactory<IPoS>(
            new BasicHttpBinding(), 
            new EndpointAddress(_address));
        _httpProxy = httpFactory.CreateChannel();
    }
}

---

最后修复了它，解决方案非常简单

只需为DTO类（在本例中为

ItemDTO

）的两端提供一个名称空间即可。

---

i、 e:

[DataContract]

到

[DataContract（名称空间“PoSDTO”）]

对我来说，这表明主机端发生了错误，但现在异常或web错误返回给了您。您可以尝试使用Fiddler调试通信。有时Fiddler会收到客户无法接收的错误消息。另外，在主机端打开日志记录并检查错误。

public partial class Item
{
    public Item()
    {
        this.Sal1 = new HashSet<Sal1>();
    }

    public string ItemID { get; set; }
    public string Name { get; set; }
    public string Manufacturer { get; set; }
    public int StockQuantity { get; set; }
    public decimal Price { get; set; }

    public virtual ICollection<Sal1> Sal1 { get; set; }
}

 public sealed class Connection {

    private readonly string _address = "http://Edwin:8080/PoS";
    private static Connection _instance;
    private static object _padLock = new Object();
    private static ChannelFactory<IPoS> httpFactory;

    private static IPoS _httpProxy; //Singleton
    public IPoS HttpProxy { get { return _httpProxy; } }

    public static Connection Instance {
        get {
            if (_instance == null) {
                lock (_padLock) {
                    if (_instance == null) {
                        _instance = new Connection();
                    }

                }
            }
            return _instance;
        }
    }

    private Connection() {
        httpFactory = new ChannelFactory<IPoS>(
            new BasicHttpBinding(), 
            new EndpointAddress(_address));
        _httpProxy = httpFactory.CreateChannel();
    }
}

[DataContract]
public class ItemDTO {
    [DataMember]
    public string ItemID { get; set; }
    [DataMember]
    public string Name { get; set; }
    [DataMember]
    public string Manufacturer { get; set; }
    [DataMember]
    public int StockQuantity { get; set; }
    [DataMember]
    public decimal Price { get; set; }
}