Serializable classes and dynamic proxies in EF - how?

In [a previous posting], I was set on the path to having to clone my entities. This I've attempted to do with a serialisation approach as found in [codeproject].

because the classes are generated by Entity Framework, I mark them up separately in a custom .cs like this:

[Serializable]
public partial class Claims
{
}

however, when the check (in the clone method):

if (Object.ReferenceEquals(source, null))
{

gets hit, I get the error:

System.ArgumentException was unhandled by user code
  Message=The type must be serializable.
Parameter name: source
  Source=Web
  ParamName=source
  StackTrace:
       at .Web.Cloner.Clone[T](T source) in C:\Users\.\Documents\Visual Studio 2010\Projects\.\Website\Extensions.Object.cs:line 49
       at .Web.Models.Employer..ctor(User u) in C:\Users\.\Documents\Visual Studio 2010\Projects\.\Website\Models\EF.Custom.cs:line 121
       at .Web.Controllers.AuthController.Register(String Company, String GivenName, String Surname, String Title, String Department) in C:\Users\.\Documents\Visual Studio 2010\Projects\.\Website\Controllers\AuthController.cs:line 119
       at lambda_method(Closure , ControllerBase , Object[] )
       at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
       at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
       at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12()
       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
  InnerException: 

so apparently whilst my class Claims is serialisable, the dynamic proxies generated by EF are not... somehow my decorations are not flowing through.

what's the trick here?

* Update I *

for more context: I have a class User which contains a property Claims defined as an ICollection<Claim>. when doing the cloning, the type that gets passed is the collection, not Claim - this explains why the cloner is complaining that the type is not serializable. so the question now is: how do I make User.Claims serializable since I can't decorate a property?

Error   1   Attribute 'Serializable' is not valid on this declaration type.
It is only valid on 'class, struct, enum, delegate' declarations.   
C:\Users\.\Documents\Visual Studio 2010\Projects\.\Website\Models\EF.Custom.cs
128 10  Website

* Update II *

the point of the exercise is to facility a deep copy. this is what it looks like:

public partial class Employer
{
    public Employer(User u)
    {
        this.Id = u.Id;
        this.GivenName = u.GivenName;
        this.Surname = u.Surname;
        this.Claims = u.Claims.Clone();
        this.Contacts = u.Contacts.Clone();
    }
}

in order for the u.Claims.Clone() to work, u.Claims must be serializable but it's not for the reasons cited above.

* Update III *

ok, I changed approach, implementing the constructor like this:

public partial class Employer
{
    public Employer(User u)
    {
        this.Id = u.Id;
        this.GivenName = u.GivenName;
        this.Surname = u.Surname;

        ICollection<Claim> cs = new List<Claim>();
        foreach (Claim c in u.Claims)
        {
            cs.Add(c.Clone());
        }
        this.Claims = cs;

and now it gets past the clone()'s check ("if" line above), but now it breaks at:

formatter.Serialize(stream, source);

with:

System.Runtime.Serialization.SerializationException was unhandled by user code
  Message=Type 'System.Data.Entity.DynamicProxies.User_7B7AFFFE306AB2E39C07D91CC157792F503F36DFCAB490FB3333A52EA1D5DC0D' in Assembly 'EntityFrameworkDynamicProxies-Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable.
  Source=mscorlib
  StackTrace:
       at System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type)
       at System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context)
       at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo()
       at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter, SerializationBinder binder)
       at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Write(WriteObjectInfo objectInfo, NameInfo memberNameInfo, NameInfo typeNameInfo)
       at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck)
       at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boolean fCheck)
       at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph)
       at Skillscore.Web.Cloner.Clone[T](T source) in C:\Users\.\Documents\Vi开发者_JS百科sual Studio 2010\Projects\.\Website\Extensions.Object.cs:line 62
       at Skillscore.Web.Models.Employer..ctor(User u) in C:\Users\.\Documents\Visual Studio 2010\Projects\.\Website\Models\EF.Custom.cs:line 130

sigh... is everything always so hard?

* Update IV *

ok, so the problem above is that the Claim class has a navigator that points back to User - which explains why the above method indicates the type to be .User_[...] and implies I need to not only make the downward dependencies serializable, but also all of the paths back up! However, having done that I successfully clone the object but I'm now back to the issue in my original posting:

System.InvalidOperationException was unhandled by user code
  Message=Conflicting changes to the role 'User' of the relationship 'EF.ClaimUser' have been detected.
  Source=System.Data.Entity
  StackTrace:
       at System.Data.Objects.DataClasses.RelatedEnd.IncludeEntity(IEntityWrapper wrappedEntity, Boolean addRelationshipAsUnchanged, Boolean doAttach)
       at System.Data.Objects.DataClasses.EntityCollection`1.Include(Boolean addRelationshipAsUnchanged, Boolean doAttach)
       at System.Data.Objects.DataClasses.RelationshipManager.AddRelatedEntitiesToObjectStateManager(Boolean doAttach)
       at System.Data.Objects.ObjectContext.AddObject(String entitySetName, Object entity)
       at System.Data.Entity.Internal.Linq.InternalSet`1.<>c__DisplayClass5.<Add>b__4()
       at System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, EntityState newState, Object entity, String methodName)
       at System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity)
       at System.Data.Entity.DbSet`1.Add(TEntity entity)
       at Skillscore.Web.Controllers.AuthController.Register(String Company, String GivenName, String Surname, String Title, String Department) in C:\Users\.\Documents\Visual Studio 2010\Projects\.\Website\Controllers\AuthController.cs:line 138

man. I need a hole in the head.

* Update V *

I don't know if the issue is the proxies or lazy loading, but after thinking about it a little, it seems that if I do a clone via serialisation, all the IDs for things that used to belong to the old object are now going to belong to the new one. I did do a .remove() first on the old object and if that has immediate effect then maybe there's something in the tracking that doesn't know about it. If it doesn't, then at one point there will be two things out there with the same ID... so I'm starting to lean towards @Jockey's idea of using object initialisers for the cloning...

---

If you want to serialize entities you can disable proxy creation before retrieving that object. You also need to eager load navigational properties if you want to serialize them as well.

To disable proxy creation in EF 4.1

dbContext.Configuration.ProxyCreationEnabled = false;

In EF 4

objectContext.ContextOptions.ProxyCreationEnabled = false;

eg:

var users = context.Users.Include("Claims").Where(/**/);

---

Look into T4 Templates for Entity Framework, you can control how EF generates your entities, you will have to define that they are serializable in the T4 Template.

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Turn off lazy loading and turn off proxy class creation. Anyway you still need to add the Serializable/DataContract attributes in order to make it serializable.

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I had the same issue using Entity Framework 6 ( EF6 ). I fixed the issue by changing the T4 template and adding the line [Serializable] between the Using Directives and the Entity Class Opening line. Like so:

 <#=codeStringGenerator.UsingDirectives(inHeader: false)#>
 [Serializable]
 <#=codeStringGenerator.EntityClassOpening(entity)#>

No other changes required.

---

As a Microsoft recommendation, you need to use DTO instead of EF entities to avoid serialization issues, consider also to use eager loading before transforming your entities to DTO.

One way to avoid serialization problems is to serialize data transfer objects (DTOs) instead of entity objects.

...

What happens if you add the corresponding navigation property [...]?

Unfortunately, this creates a problem when you serialize the models. If you load the related data, it creates a circular object graph.

One solution is to use DTOs, [...] Alternatively, you can configure the JSON and XML formatters to handle graph cycles.

EF Documentation - How to create a Web API application that uses Entity Framework for database persistence.