未在服务中实现接口成员

Question

First of all I apologize if the references to this question are not correct.

I am developing a three-tier MVC 3 application. In the business layer I need to create a service which will call the Data Access Layer, in order to retrieve a list of existing towns.

My ITown interface is as follows;

[ServiceContract]
public interface ITown
{
    [OperationContract]
    IEnumerable<Town> GetAllTowns();
}

In the Town.svc.cs , I am inserting as follows;

public class Town : ITown
{
    public IEnumerable<Common.Town> GetAllTowns()
    {
        return new DATown().GetAllTowns();
    }
}

The problem is in the above code. I am getting an error under Town in the class declaration public class Town : ITown .

'Business.Town' does not implement interface member 'Business.ITown.GetAllTowns()'. 
'Business.Town.GetAllTowns()' cannot implement 'Business.ITown.GetAllTowns()'
because it does not have the matching return type of 'System.Collections.Generic.IEnumerable<Business.Town>'.

This is the content in my DATown ;

public class DATown : Connection
{
    //Constructor
    public DATown()
        :base()
    { }

    public IEnumerable<Town> GetAllTowns()
    {
        return entities.Town.AsEnumerable();
    }
}

So basically what I am doing is calling the GetAllTowns() method of DATown from the Town.svc.cs class.

I've searched around for other similar queries; mostly saying that there is a correct parameter in one of the methods. I do not think that this is the case with my code.

I would appreciate if someone could help me figure out what is wrong.

Thanks in advance.

Answer 1

In your Town class you have an IEnumerable<Common.Town> and in the interface you've simply got IEnumerable<Town> , but in your error it shows that the interface is using Business.Town and not Common.Town . The issue is that these are not the same as each other.

If you change your Interface so the IEnumerable is also of Common.Town you should be ok.

Answer 2

From what I see, you've got an incorrect return type - your Town in ITown is Bussiness.Town, whereas in the service class you return Common.Town. Try returning Bussiness.Town in svc