OK… I’ve looked on the web and found two possible solutions to my issue of not being able to return an IEnumerable type in a .Net 4.0 WCF service.
See below link. This is exactly what I’m getting when I am executing the WCF Test Client tool and trying to invoke a method.
https://connect.microsoft.com/wcf/feedback/details/336696/ienumerable-t-serialization-bug
Mind you, to be sure there is nothing wrong with my web service, I am able to return a type of this object for a single record, just not an IEnumerable.
Both solutions that I have tried, shown below do not work for me. I get the same error. This is driving me crazy. I know what the issue is, followed steps to circumvent the issue, but I am still getting the same error.
How can I resolve this?
This is the first solution I tried: Note that I even tried removing the “ToList” and “ToArray” on the last statement in each of the methods because it’s implied already.
Interface
[OperationContract]
IList<Priority> GetPriorities();
Method
public IList<Priority> GetPriorities()
{
YeagerTechEntities DbContext = new YeagerTechEntities();
IList<Priority> priority = DbContext.Priorities.Where(p => p.PriorityID > 0).ToList();
CloseConnection(DbContext);
return priority.ToList();
}
This is the second solution I tried:
Interface
[OperationContract]
Priority[] GetPriorities();
Method
public Priority[] GetPriorities()
{
YeagerTechEntities DbContext = new YeagerTechEntities();
Priority[] priority = DbContext.Priorities.Where(p => p.PriorityID > 0).ToArray();
CloseConnection(DbContext);
return priority.ToArray();
}
Here it is with a List instead of an IList which still doesn’t work.
Interface
[OperationContract]
List<Priority> GetPriorities();
Method
public List<Priority> GetPriorities()
{
YeagerTechEntities DbContext = new YeagerTechEntities();
List<Priority> priority = DbContext.Priorities.Where(p => p.PriorityID > 0).ToList();
CloseConnection(DbContext);
return priority.ToList();
}
Notice that the below method works fine when retrieving just one object instead of a list.
[OperationContract]
Priority GetPriorityID(Int16 priorityid);
public Priority GetPriorityID(Int16 priorityid)
{
YeagerTechEntities DbContext = new YeagerTechEntities();
Priority priority = null;
var priorityEntity = (from p in DbContext.Priorities
where p.PriorityID == priorityid
select p).FirstOrDefault();
if (priorityEntity != null)
{
priority = new Priority();
priority.PriorityID = priorityEntity.PriorityID;
priority.Description = priorityEntity.Description;
CloseConnection(DbContext);
}
else
{
CloseConnection(DbContext);
throw new Exception("Priority " + priorityid + " not found!");
}
return priority;
}
The entire error msg from the wcf test client for the first method in this post is as follows. What is the resolution in order to be able to return a list of objects?
Failed to invoke the service. Possible causes: The service is offline or inaccessible; the client-side configuration does not match the proxy; the existing proxy is invalid. Refer to the stack trace for more detail. You can try to recover by starting a new proxy, restoring to default configuration, or refreshing the service.
An error occurred while receiving the HTTP response to http://localhost:8732/Design_Time_Addresses/YeagerTechWcfService/YeagerTechWcfService/. This could be due to the service endpoint binding not using the HTTP protocol. This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down). See server logs for more details.
Server stack trace:
at System.ServiceModel.Channels.HttpChannelUtilities.ProcessGetResponseWebException(WebException webException, HttpWebRequest request, HttpAbortReason abortReason)
at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.ClientReliableChannelBinder1.RequestClientReliableChannelBinder1.OnRequest(TRequestChannel channel, Message message, TimeSpan timeout, MaskingMode maskingMode)
at System.ServiceModel.Channels.ClientReliableChannelBinder1.Request(Message message, TimeSpan timeout, MaskingMode maskingMode)1.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.ClientReliableChannelBinder
at System.ServiceModel.Security.SecuritySessionClientSettings`1.SecurityRequestSessionChannel.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
at IYeagerTechWcfService.GetPriorities()
at YeagerTechWcfServiceClient.GetPriorities()
Inner Exception:
The underlying connection was closed: An unexpected error occurred on a receive.
at System.Net.HttpWebRequest.GetResponse()
at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
Inner Exception:
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.PooledStream.Read(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.Connection.SyncRead(HttpWebRequest request, Boolean userRetrievedStream, Boolean probeRead)
Inner Exception:
An existing connection was forcibly closed by the remote host
at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)
at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
I modified my classes (see below), but am still getting the same exact error.
Surely, there must be someone who has tried this before where they get an object back from Entity Framework and want to pass it back as an IEnumerable. I’m very frustrated with this. Please help me out…
Based on my previous post, my classes are exactly the same with the following changes. I tried two methodologies.
Please refer to the first and second scenarios separately.
First scenario for Interface
I tried using just the Customer class and then an IEnumerable declaration of it.
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
using YeagerTechModel;
namespace YeagerTechWcfService
{
//[ServiceKnownType(typeof(YeagerTechModel.Customer))]
[ServiceKnownType(typeof(IEnumerable<YeagerTechModel.Customer>))]
[ServiceContract]
public interface IYeagerTechWcfService
{
[OperationContract]
IEnumerable<Customer> GetCustomers();
[OperationContract]
Customer GetCustomerID(Int16 customerid);
It resides in my YeagerTechModel project in the same solution referenced by my web service (the other project in the same solution).
First scenario for Customer object
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ServiceModel;
using System.Runtime.Serialization;
namespace YeagerTechModel
{
[Serializable]
[DataContract]
public partial class Customer
{
public Customer()
{
this.Projects = new HashSet<Project>();
}
[DataMember]
public short CustomerID { get; set; }
[Required]
[StringLength(50)]
[DataType(DataType.EmailAddress)]
[DataMember]
public string Email { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Company { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string FirstName { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string LastName { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Address1 { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Address2 { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string City { get; set; }
[StringLength(2)]
[DataType(DataType.Text)]
[DataMember]
public string State { get; set; }
[StringLength(10)]
[DataType(DataType.Text)]
[RegularExpression(@"^\d{5}(-\d{4})?$")]
[DataMember]
public string Zip { get; set; }
[StringLength(12)]
[DataType(DataType.PhoneNumber)]
public string HomePhone { get; set; }
[StringLength(12)]
[DataType(DataType.PhoneNumber)]
[DataMember]
public string CellPhone { get; set; }
[StringLength(100)]
[DataType(DataType.Url)]
[DataMember]
public string Website { get; set; }
[StringLength(50)]
[DataType(DataType.EmailAddress)]
[DataMember]
public string IMAddress { get; set; }
[DataMember]
public System.DateTime CreatedDate { get; set; }
[DataMember]
public Nullable<System.DateTime> UpdatedDate { get; set; }
public virtual ICollection<Project> Projects { get; set; }
}
Second scenario for interface:
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;
using YeagerTechModel;
namespace YeagerTechWcfService
{
[ServiceContract]
public interface IYeagerTechWcfService
{
[OperationContract]
IEnumerable<Customer> GetCustomers();
[OperationContract]
Customer GetCustomerID(Int16 customerid);
Second scenario for Customer object
I have tried using just the Customer class and then an IEnumerable declaration of it at the bottom of this class.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ServiceModel;
using System.Runtime.Serialization;
namespace YeagerTechModel
{
[KnownTypeAttribute("KnownTypes")]
[Serializable]
[DataContract]
public partial class Customer
{
public Customer()
{
this.Projects = new HashSet<Project>();
}
[DataMember]
public short CustomerID { get; set; }
[Required]
[StringLength(50)]
[DataType(DataType.EmailAddress)]
[DataMember]
public string Email { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Company { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string FirstName { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string LastName { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Address1 { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Address2 { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string City { get; set; }
[StringLength(2)]
[DataType(DataType.Text)]
[DataMember]
public string State { get; set; }
[StringLength(10)]
[DataType(DataType.Text)]
[RegularExpression(@"^\d{5}(-\d{4})?$")]
[DataMember]
public string Zip { get; set; }
[StringLength(12)]
[DataType(DataType.PhoneNumber)]
public string HomePhone { get; set; }
[StringLength(12)]
[DataType(DataType.PhoneNumber)]
[DataMember]
public string CellPhone { get; set; }
[StringLength(100)]
[DataType(DataType.Url)]
[DataMember]
public string Website { get; set; }
[StringLength(50)]
[DataType(DataType.EmailAddress)]
[DataMember]
public string IMAddress { get; set; }
[DataMember]
public System.DateTime CreatedDate { get; set; }
[DataMember]
public Nullable<System.DateTime> UpdatedDate { get; set; }
public virtual ICollection<Project> Projects { get; set; }
static Type[] KnownTypes()
{
return new Type[] { typeof(IEnumerable<Customer>) };
}
}
I tried:
return customer;
return customer.ToList();
return customer.ToArray();
public IEnumerable<Customer> GetCustomers()
{
YeagerTechEntities DbContext = new YeagerTechEntities();
IEnumerable<Customer> customer = DbContext.Customers.Where(p => p.CustomerID > 0);
CloseConnection(DbContext);
return customer;
}
The problem seems to be a serialization issue when trying to pass back the Customer object which is part of an Entity Framework model. There has to be a documented way of passing back an object of this type which is derived from an Entity Framework model.
Where is it????
Here is the latest of what I tried and am still getting the same exact error….
namespace YeagerTechWcfService
{
[ServiceContract]
public interface IYeagerTechWcfService
{
[OperationContract]
List<Customer> GetCustomers();
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ServiceModel;
using System.Runtime.Serialization;
namespace YeagerTechModel
{
[Serializable]
[DataContract]
public partial class Customer
{
public Customer()
{
this.Projects = new HashSet<Project>();
}
[DataMember]
public short CustomerID { get; set; }
[Required]
[StringLength(50)]
[DataType(DataType.EmailAddress)]
[DataMember]
public string Email { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Company { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string FirstName { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string LastName { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Address1 { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string Address2 { get; set; }
[StringLength(50)]
[DataType(DataType.Text)]
[DataMember]
public string City { get; set; }
[StringLength(2)]
[DataType(DataType.Text)]
[DataMember]
public string State { get; set; }
[StringLength(10)]
[DataType(DataType.Text)]
[RegularExpression(@"^\d{5}(-\d{4})?$")]
[DataMember]
public string Zip { get; set; }
[StringLength(12)]
[DataType(DataType.PhoneNumber)]
public string HomePhone { get; set; }
[StringLength(12)]
[DataType(DataType.PhoneNumber)]
[DataMember]
public string CellPhone { get; set; }
[StringLength(100)]
[DataType(DataType.Url)]
[DataMember]
public string Website { get; set; }
[StringLength(50)]
[DataType(DataType.EmailAddress)]
[DataMember]
public string IMAddress { get; set; }
[DataMember]
public System.DateTime CreatedDate { get; set; }
[DataMember]
public Nullable<System.DateTime> UpdatedDate { get; set; }
public virtual ICollection<Project> Projects { get; set; }
}
public List<Customer> GetCustomers()
{
YeagerTechEntities DbContext = new YeagerTechEntities();
List<Customer> customer = DbContext.Customers.Where(p => p.CustomerID > 0).ToList();
return customer.ToList();
}
The answer was as simple as setting a property to false before making my EF call to the database.
DbContext.Configuration.ProxyCreationEnabled = false;
EF automatically generates a proxy class. Dynamic Proxies – They don’t play nice over the wire – Turn these off (ContextOptions.ProxyCreationEnabled == false).