How to pass Interface as parameter in WCF service?

Question

I have the following however I am not sure this is the correct way of doing it.

namespace WCFServices
{
    [ServiceContract(Name = "IService")]
    [ServiceKnownTypeAttribute(typeof(DataItem))]
    public interface IService
    {
        [OperationContract]
        void InstantiateThirdParties(string name, IEnumerable<IDataItem> data, IEnumerable<string> modules, IEnumerable<string> states);
    }
}

this is the code that uses the interface.

namespace WCFServices
{
    public class Service : IService
    {
        public void InstantiateThirdParties(string name, IEnumerable<IDataItem> data, IEnumerable<string> modules, IEnumerable<string> states)
        {
            Process.ExecuteAll(name, data, modules, states);
        }
    }
}

and my only object type at the moment is the following.

namespace DataObjects
{
    [Serializable]
    [DataContract]
    public class DataItem : IDataItem
    {
        public DataItem();

        [DataMember]
        public CustomerInfo customer { get; set; }

        [DataMember]
        public LoanInfo loan { get; set; }

        [DataMember]
        public DateTime loanProcessingDate { get; set; }

        [DataMember]
        public string moduleID { get; set; }

        [DataMember]
        public string processingState { get; set; }
    }
}

am I headed in the right direction?

What exactly are you trying to achieve? Parameter that does what? — Jerrington, Oct 28 '14 at 15:14
The WCF service takes in 4 paratmers. One happens to be an interface type of IDataItem. I need to tell the service what kind of objects take that interface correct? — Tyler Buchanan, Oct 28 '14 at 15:16
The only interfaces involved here are `IEnumerable, `IDataItem` and `IService`. What exactly do you mean? — Codor, Oct 28 '14 at 15:22
found the answer on this post... http://stackoverflow.com/questions/7213083/using-class-interface-as-a-parameter-in-wcf-service — Tyler Buchanan, Mar 26 '15 at 21:20

score 2 · Accepted Answer · answered Oct 28 '14 at 15:28

2

You need to use the KnownTypeAttribute instead of the ServiceKnownTypeAttribute.

answered Oct 28 '14 at 15:28

papadi

985
2
9
22

Ok, where do I put this annotation? is it like my answer? – Tyler Buchanan Oct 28 '14 at 16:00
I think it should work if you put it on top of IService. But normally I would put it on top of IDataItem for better encapsulation. – papadi Oct 28 '14 at 19:26

Jerrington · Answer 2 · 2014-10-28T16:27:07.903

1

If the interface in question is your IDataItem which is used in the IEnumerable<IDataItem> parameter then you need to mark the interface itself as a known type:

[KnownTypeAttribute(typeof(IDataItem))]

Check this blog: http://blogs.msdn.com/b/domgreen/archive/2009/04/13/wcf-using-interfaces-in-method-signatures.aspx

Edit: Should be KnownTypeAttribute not ServiceKnownTypeAttribute as papadi pointed out correctly.

Edit 2:

namespace WCFServices
{
    [ServiceContract(Name = "IService")]
    [ServiceKnownTypeAttribute(typeof(DataItem))]
    public interface IService
    {
        [OperationContract]
        void InstantiateThirdParties(string name, IEnumerable<IDataItem> data, IEnumerable<string> modules, IEnumerable<string> states);
    }
}

namespace DataObjects
{
    [DataContract]
    [KnownType(typeof(IDataItem))]
    public class DataItem : IDataItem
    {
        ...
    }
}

edited Oct 28 '14 at 16:27

answered Oct 28 '14 at 15:26

Jerrington

113
4

Ok where do I put this annotation? such as below? – Tyler Buchanan Oct 28 '14 at 15:56
@TylerBuchanan, yes, your own answer seems correct. Does that not work? Are you getting any error messages? – Jerrington Oct 28 '14 at 16:10
It says "Attribute 'KnownTypeAttribute' is not valid on this declaration type. it is only valid on 'class, struct' declarations." – Tyler Buchanan Oct 28 '14 at 16:15

Tyler Buchanan · Answer 3 · 2014-10-28T22:57:26.813

Do you mean like the following?

namespace WCFServices
{
    [ServiceContract(Name = "IService")]
    [KnownTypeAttribute(typeof(DataItem))]
    public interface IService
    {
        [OperationContract]
        void InstantiateThirdParties(string name, IEnumerable<IDataItem> data, IEnumerable<string> modules, IEnumerable<string> states);
    }
}

With my Object still looking like this.

namespace DataObjects
{
    [DataContract]
    [Serializable]   <------ Not having this was my problem
    [KnownType(typeof(IDataItem))]
    public class DataItem : IDataItem
    {
        public DataItem();

        [DataMember]
        public CustomerInfo customer { get; set; }
        [DataMember]
        public LoanInfo loan { get; set; }
        [DataMember]
        public DateTime loanProcessingDate { get; set; }
        [DataMember]
        public string moduleID { get; set; }
        [DataMember]
        public string processingState { get; set; }
    }
}

here is my interface

namespace Interfaces
{
    public interface IDataItem
    {
        CustomerInfo customer { get; set; }
        LoanInfo loan { get; set; }
        DateTime loanProcessingDate { get; set; }
        string moduleID { get; set; }
        string processingState { get; set; }
    }
}

Sorry, I take it back, your answer is not entirely correct. In your service declaration you need `ServiceKnownTypeAttribute` not `KnownTypeAttribute` (`DataItem` class is marked correctly). — Jerrington, Oct 28 '14 at 16:19
Filled out a SoapUI request for the service and I am getting everything except the data parameter. The list is empty. — Tyler Buchanan, Oct 28 '14 at 17:30

How to pass Interface as parameter in WCF service?

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