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当我在 EF4 和 WCF 中实现 STE 时收到此错误

“找不到标识为 'NorthwindModel.Customer' 的类型的对象映射。”

如果我不使用 STE（在单个项目中），则此代码有效。

演练：序列化自我跟踪实体

这是我的代码

周转基金：

Public Class Service1
Implements IService1

  Public Function GetData(ByVal query As String) As List(Of DbDataRecord) Implements IService1.GetData
  Try
     Using ctx = New NorthwindEntities()
        Return New ObjectQuery(Of DbDataRecord)(query, ctx).ToList 'Here is the error.
     End Using
  Catch ex As Exception
     Dim theFault As New ServFault()
     theFault.Reason = ex.Message.ToString()
     Throw New FaultException(Of ServFault)(theFault, ex.Message.ToString)
  End Try
End Function

Public Function GetOrderByCustomer(customerId As String) As System.Collections.Generic.List(Of Entities.Order) Implements IService1.GetOrderByCustomer
  Try
     Using ctx = New NorthwindEntities()
        Return (From ord In ctx.Orders Where ord.CustomerID = customerId).ToList
     End Using
  Catch ex As Exception
     Dim theFault As New ServFault()
     theFault.Reason = ex.Message.ToString()
     Throw New FaultException(Of ServFault)(theFault, ex.Message.ToString)
  End Try

End Function
End Class

WCF 配置

<?xml version="1.0"?>
<configuration>

  <system.web>
    <compilation debug="true" strict="false" explicit="true" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
          <serviceMetadata httpGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>
   <connectionStrings>
      <add name="NorthwindEntities" connectionString="metadata=res://*/NWDModel.csdl|res://*/NWDModel.ssdl|res://*/NWDModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=(local);initial catalog=Northwind;persist security info=True;user id=sa;password=145837;multipleactiveresultsets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />
   </connectionStrings>
</configuration>

WCF 客户端：

Module Module1

   Sub Main()
      Dim srv As New Service1Client
      Dim query As String
      Dim lst As List(Of DbDataRecord)

      Console.WriteLine("Start...")

      Dim orders As List(Of Entities.Order)
      orders = srv.GetOrderByCustomer("ALFKI") 'This code is working
      Console.WriteLine("Success!!! Order Count: {0}", orders.Count)

      query = "SELECT p FROM Customers AS p"
      lst = srv.GetData(query)

      Console.WriteLine("Total Customer: {0}", lst.Count)

      srv.Close()
      Console.ReadLine()
   End Sub

End Module

希望有人可以指导我。如果您需要，也可以提供上述示例的完整来源

4

1 回答 1

0

这不适用于 WCF。您必须始终发回真实的实体类型，而不是DbDataRecord抽象类。WCF 必须知道使用的真实类型是什么。EF 中的真实类型可能MaterializedDbRecord是内部的且不可序列化的。

通过 WCF 公开方法时，您必须使用简单类型或数据协定/序列化类型作为参数和结果。STE 是数据合同，因此请直接使用它们 - 这显然会破坏您从客户端发送无类型查询的要求，但这不是 WCF 的场景。

如果您正在寻找允许您在客户端上创建查询的技术，请检查WCF 数据服务（但它们不支持 STE）。

于 2011-11-29T09:16:22.040 回答