Question

这是我想要做的：

我有一个现有的数据库，我需要从中获取数据。
我创建了数据合同，通过使用Entity Framework将它们映射到各个表。在我的例子中，我有三个表 - tblOrder，tblProduct和tblCustomer。所以我创建了三个数据合同来映射到这些表。实体框架注释已添加到数据承诺中。我写了一个单元测试来测试我的数据合同。通过直接的Entity Framework调用，一切都按预期工作。见下面的单元测试1.
为每个数据协定添加了DataServiceKey批注。并通过添加订单上下文和数据服务svc将它们与OData服务包装在一起。见下文。
写了一个单元测试，通过OData服务访问一些现有的订单数据。问题：OData服务仅返回Order对象上的非自定义数据类型。它在客户数据类型字段（例如CustomerInfo和ProductList）上返回null。

我做错了吗？对于使用EF进行检索的OData调用来处理对象有什么特别之处吗？

[DataServiceKey("ID")]      
[Table("tblOrder", Schema = "schOnlineSale")]      
public class Order     
{     

     [Column("OrderId"), Key]        
     public int ID { get; set; }

     public string OrderName { get; set; }

     public int CustomerId { get; set; }

     [ForeignKey("CustomerId")]
     public virtual Customer CustomerInfo { get; set; }

     [ForeignKey("OrderId")]
     public virtual ICollection<Product> ProductList{ get; set; }
}

[DataServiceKey("CustomerId")]     
[Table("tblCustomer", Schema = "schOnlineSale")]     
public class Customer    
{

     [Key]
     public int CustomerId{ get; set; }

     [Column("FullName")]
     public string Name { get; set; }

     public string MailingAddress { get; set; }   
     public string City { get; set; }   
     public string State { get; set; }   
     public string ZIPCode { get; set; }   
}

[DataServiceKey("ProductId")]   
[Table("tblProduct", Schema = "schOnlineSale")]    
public class Product    
{

     [Key]
     public int ProductId{ get; set; }

     public int OrderId{ get; set; }

     public string ProductName { get; set; }

     public decimal SalePrice { get; set; }   
}

//OData Service wrapper classes    
public class OrderContext:  DbContext    
{        

     public DbSet<Order> Orders {get; set;}

     public DbSet<Product> Products {get; set;}
}

[ServiceBehavior(IncludeExceptionDetailInFaults = true)]   
public class OrderDataService : DataService<OrderContext>    
{

        // This method is called only once to initialize service-wide policies.
        public static void InitializeService(DataServiceConfiguration config)
        {
            config.SetEntitySetAccessRule("Orders", EntitySetRights.All);
            config.SetEntitySetAccessRule("Products", EntitySetRights.All);
            config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
            config.UseVerboseErrors = true;
        }

        protected override void HandleException(HandleExceptionArgs args)
        {
            try
            {
                args.UseVerboseErrors = true;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }

        protected override OrderContext CreateDataSource()
        {
            var dataSource = new OrderContext();
            dataSource.Configuration.ProxyCreationEnabled = false;
            return dataSource;            
        }
    }

//Unit Test 1 - Querying via data context directly
public void EFDataContext_GetOrderTest()
{            
    var context = new OrderContext();            
    var list = (from a in context.Orders 
          where a.OrderId == 10 || 
                a.OrderId == 15 ||
                a.OrderId== 20 select a).ToList();

    //CustomerInfo and ProductList values are populated properly
}


//Unit test 2 - Querying via OData Service
public void OData_GetOrderTest()
{
  string uriString = "http://localhost/OrderServices/OrderDataService.svc/Orders(10)";
  Uri serviceUri = new Uri(uriString);
  OrderContext context = new OrderContext(serviceUri);
  context.IgnoreResourceNotFoundException = true;
  var orderList = context.Orders;            

  foreach (Order s in orderList)
  {
     TestContext.WriteLine("OrderId=" + s.ID);

     Assert.IsNotNull(s.CustomerInfo);  //CustomerInfo is not returned with OData call
                                  //but it's returned properly with entity framework call.

     foreach (Product p in s.ProductList)
     {
        //ProductList is also not returned with OData Service call,
        //but it is returned properly when accessing through Entity Framework calls     
        //directly
     }

   }            
}

//app.config   
<configuration>    
  <connectionStrings>    
    <add name="OrderContext" connectionString="a valid connection string" providerName="System.Data.SqlClient" />    
  </connectionStrings>    
</configuration>

Answer 1

OData（或者在本例中为WCF数据服务客户端）不会延迟加载导航属性（这是从关系创建的属性被调用的）。你必须明确地要求它。

您可以预先执行此操作，通过展开，您可以要求原始查询在导航属性的另一侧包含实体。只需在查询中添加.Expand（“订单”）即可获得订单实体以及客户。

您也可以稍后通过context.LoadProperty方法执行此操作。

OData服务不返回自定义对象

1 个答案: