使用WCF 4.0的Entity Framework 4.0 DataContractSerializer错误 [英] DataContractSerializer Error using Entity Framework 4.0 with WCF 4.0

问题描述

我尝试通过WCF从Entity框架中检索对象列表，但是收到以下异常：尝试序列化参数< a href =http://tempuri.org/:GetAllResult =noreferrer> http://tempuri.org/:GetAllResult 。设置InnerException消息是 '类型 'System.Data.Entity.DynamicProxies.TestObject_240F2B681A782799F3A0C3AFBE4A67A7E86083C3CC4A3939573C5410B408ECCE' 与数据合同名' TestObject_240F2B681A782799F3A0C3AFBE4A67A7E86083C3CC4A3939573C5410B408ECCE： http://schemas.datacontract.org/2004/07/System.Data.Entity.DynamicProxies '不是预期的。考虑使用DataContractResolver或将已知类型列表中不知道的任何类型添加到已知类型列表中，例如使用KnownTypeAttribute属性或将其添加到传递给DataContractSerializer的已知类型的列表中。请参阅InnerException了解更多详细信息。

我过去使用过WCF，但从未使用实体框架。我有通过实体框架生成的所有实体，并用[DataContract]和[DataMember]属性注释。我的任何实体都没有导航属性。

正在调用的GetAll（）方法在抽象服务类中：

  [ServiceContract] 
 public interface IService< T> 
 {
 [OperationContract] 
列表< T>得到所有（）; 
} 
  

我正在使用ChannelFactory来调用我的实现：

 绑定绑定=新的NetTcpBinding（）; 
 EndpointAddress endpointAddress = new EndpointAddress（net.tcp：// localhost：8081 /+ typeof（TestObjectService）.Name）; 
使用（ChannelFactory< ITestObjectService> channel = new ChannelFactory< ITestObjectService>（binding，endpointAddress））
 {
 ITestObjectService testObjectService = channel.CreateChannel（）; 
 testObjects = testObjectService.GetAll（）; 
 channel.Close（）; 
} 
  

我正在托管它：

 类型t​​ype = typeof（TestObjectService）; 
 ServiceHost host = new ServiceHost（type，
 new Uri（http：// localhost：8080 /+ type.Name），
 new Uri（net.tcp：// localhost ：8081 /+ type.Name））; 
 host.Open（）; 
  

当使用调试时，它会从数据库中找到对象，但是它返回对象失败。

有什么想法可能会出错？

解决方案

这是一个痛苦的想法，但它是因为EntityFramework创建一个代理您的类。 TestObject类已经正确安装，但它正在创建一个名为TestObject_240F2B681A782799F3A0C3AFBE4A67A7E86083C3CC4A3939573C5410B408ECCE的类。

为了使ChannelFactory + WCF +实体框架全部协同工作，您必须进入您的Context构造函数并添加以下内容：

  ContextOptions.ProxyCreationEnabled = false; 
  

我希望这有助于别人。

I am attempting to retrieve a list of objects from Entity Framework via WCF, but am receiving the following exception:

There was an error while trying to serialize parameter http://tempuri.org/:GetAllResult. The InnerException message was 'Type 'System.Data.Entity.DynamicProxies.TestObject_240F2B681A782799F3A0C3AFBE4A67A7E86083C3CC4A3939573C5410B408ECCE' with data contract name 'TestObject_240F2B681A782799F3A0C3AFBE4A67A7E86083C3CC4A3939573C5410B408ECCE:http://schemas.datacontract.org/2004/07/System.Data.Entity.DynamicProxies' is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.'. Please see InnerException for more details.

I have used WCF in the past, but never with Entity Framework. I have all my entities generated via Entity Framework and are annotated with [DataContract] and [DataMember] attributes. I have no Navigation Properties on any of my entities.

The GetAll() method being called is in an abstract service class:

[ServiceContract]
public interface IService<T>
{
    [OperationContract]
    List<T> GetAll();
}

And I am using the ChannelFactory to call my implementation:

Binding binding = new NetTcpBinding();
EndpointAddress endpointAddress = new EndpointAddress("net.tcp://localhost:8081/" + typeof(TestObjectService).Name);
using (ChannelFactory<ITestObjectService> channel = new ChannelFactory<ITestObjectService>(binding, endpointAddress))
{
    ITestObjectService testObjectService = channel.CreateChannel();
    testObjects = testObjectService.GetAll();
    channel.Close();
}

I am hosting it as such:

Type type = typeof(TestObjectService);
ServiceHost host = new ServiceHost(type,
            new Uri("http://localhost:8080/" + type.Name),
            new Uri("net.tcp://localhost:8081/" + type.Name));
host.Open();

When using debugging, it finds the objects from the database, however, it is failing returning the objects.

Any ideas as to where I may be going wrong?

解决方案

This was a pain to figure out but it is because EntityFramework creates a 'proxy' of your class. The TestObject class I had was setup correctly, but it was creating a class called: TestObject_240F2B681A782799F3A0C3AFBE4A67A7E86083C3CC4A3939573C5410B408ECCE

To make the ChannelFactory + WCF + Entity Framework all work together, you must go into your Context constructor and add the following:

ContextOptions.ProxyCreationEnabled = false;

I hope this helps someone else.

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