Return Entity Framework objects over WCF

Question

We have a problem concerning Entity Framework objects and sending them through WCF. We have a database, and Entity Framework created classes from that database, a 'Wallet' class in this particular situation.

We try to transfer a Wallet using this code:

public Wallet getWallet()
{
    Wallet w = new Wallet();
    w.name = "myname";
    w.walletID = 123;
    return w;
}

We need to transfer that Wallet class, but it won't work, we always encounter the same exception:

"An error occurred while receiving the HTTP response to localhost:8860/ComplementaryCoins.svc. 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."

We searched on the internet, and there is a possibility that the error is due to the need of serialization of Entity Framework-objects.

We have absolutely no idea if this could be the case, and if this is the case, how to solve it. Our DataContract looks like this (very simple):

[DataContract]
public partial class Wallet
{
    [DataMember]
    public int getwalletID { get { return walletID; } }
    [DataMember]
    public string getname { get { return name; } }
}

Does anyone ever encountered this problem?

EDIT: Our Entity Framework created class looks like this:

namespace ComplementaryCoins
{
    using System;
    using System.Collections.Generic;

    public partial class Wallet
    {
        public Wallet()
        {
            this.Transaction = new HashSet<Transaction>();
            this.Transaction1 = new HashSet<Transaction>();
            this.User_Wallet = new HashSet<User_Wallet>();
            this.Wallet_Item = new HashSet<Wallet_Item>();
        }

        public int walletID { get; set; }
        public string name { get; set; }

        public virtual ICollection<Transaction> Transaction { get; set; }
        public virtual ICollection<Transaction> Transaction1 { get; set; }
        public virtual ICollection<User_Wallet> User_Wallet { get; set; }
        public virtual ICollection<Wallet_Item> Wallet_Item { get; set; }
    }
}

Thanks for helping us.

Can you edit the question to include the code which returns the Wallet from the WCF service. Also, this is marked as a partial class - is there another half to it? — RB.
– RB., Commented Mar 7, 2013 at 8:38
It is partial, because, like I stated, LINQ already created a Wallet class from our database. I added the code which returns a Wallet. — Mathias Maes
– Mathias Maes, Commented Mar 7, 2013 at 8:41
LINQ cannot create a Wallet class - it is a query language. Are you using something like database-first Entity Framework, or a similar ORM? — RB.
– RB., Commented Mar 7, 2013 at 8:46
I don't get it. How do you expect the receiving end to fill the Wallet object if the members are read-only? — adrianm
– adrianm, Commented Mar 7, 2013 at 8:51
Indeed, I wasn't aware of that (we're just learning the subject). It is indeed the Entity Framework that created the classes. — Mathias Maes
– Mathias Maes, Commented Mar 7, 2013 at 8:53

Nawed Nabi Zada · Accepted Answer · 2013-08-02 09:07:58Z

16

I had the same problem some time ago and the solution for this was:

The entity framework was returning a serialized class instead of normal class. eg. Wallet_asfawfklnaewfklawlfkawlfjlwfejlkef instead of Wallet

To solve that you can add this code:

base.Configuration.ProxyCreationEnabled = false;

in your Context file. Since the context file is auto generated you can add it in the Context.tt In the Context.tt file it can be added around lines 55-65:

<#=Accessibility.ForType(container)#> partial class <#=code.Escape(container)#> : DbContext
{
public <#=code.Escape(container)#>()
    : base("name=<#=container.Name#>")
{
base.Configuration.ProxyCreationEnabled = false;
<#
if (!loader.IsLazyLoadingEnabled(container))
{
#>
    this.Configuration.LazyLoadingEnabled = false;
<#

answered Aug 2, 2013 at 9:07

Nawed Nabi Zada

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1 Comment

oo_dev Over a year ago

Great, you are a hero!

andri · Accepted Answer · 2013-03-07 09:15:28Z

1

Try specifying a setter for the properties, something like this :

[DataContract]
public partial class Wallet
{
    [DataMember]
    public int getwalletID { get { return walletID; } set { } }
    [DataMember]
    public string getname { get { return name; } set { } }
}

If it still doesn't work, you may consider creating an intermediate POCO class for this purpose, and use mapper library like AutoMapper or ValueInjecter to transfer the data from the EF objects.

The POCO class should have same properties as your EF class :

[DataContract]
public class WalletDTO
{
    [DataMember]
    public int walletID { get; set; }
    [DataMember]
    public string name { get; set; }
}

And modify your method to return this class instead :

public WalletDTO getWallet()
{
    Wallet w = new Wallet(); // or get it from db using EF

    var dto = new WalletDTO();        
    //assuming we are using ValueInjecter, this code below will transfer all matched properties from w to dto
    dto.InjectFrom(w); 
    return dto;
}

edited Mar 7, 2013 at 9:15

answered Mar 7, 2013 at 8:54

andri

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2 Comments

Mathias Maes Over a year ago

While your solution looks nice, could it be possible that ValueInjecter is not compatible with .NET 4.5?

andri Over a year ago

I'm not sure about ValueInjecter compatibility with 4.5, but the solution I'm suggesting is mainly about the POCO class, not the mapper library. Especially in your case, where only two properties involved, doing the mapping manually still make sense. Or you can try another mapping library : AutoMapper, EmitMapper, etc. I hope you get the idea.

AakashM · Accepted Answer · 2013-03-07 09:22:04Z

0

Are you trying to recieve a IEnumerable<Wallets>? If - yes, please modify your server class that returns the IEnumerable by adding .ToArray() method

edited Mar 7, 2013 at 9:22

AakashM

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answered Mar 7, 2013 at 8:43

Yaugen Vlasau

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1 Comment

Mathias Maes Over a year ago

No, we're just trying to recieve a Wallet object.

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