Question

I’ve come onto a problem which I can’t find a good solution to – I’ve got a WCF service, where I want to return an object of ChildClass which inherits from FatherClass.

Mostly, I’d return the ChildClass, but in some cases I’d like to return just the FatherClass (which holds just 1 field “error”).

Can this be accomplished?

My Code:

[WebGet(UriTemplate = "SomeQueryString", ResponseFormat = System.ServiceModel.Web.WebMessageFormat.Json)]
public ChildClass GetCollection(parameter)
{

    if (err)
    {
        return new FatherClass();
    }
    else
    {
        return new ChildClass();
    }
}

Where as ChildClass inherits from FatherClass (has less fields).

My objective is to return only a very small fraction of the “text” instead of the text that will be returned if I return the whole ChildClass object.

Ideas? 🙂

Thanks!

Answer 1

That is possible only if you redefine your operation and contracts – you must return parent and serializer must know about all children which can be used instead of the parent:

[KnownType(typeof(ChildClass)]
[DataContract]
public class ParentClass 
{
    // DataMembers
}

[DataContract]
public class ChildClass : ParentClass 
{
    // DataMembers
}

And your operation will look like:

[WebGet(UriTemplate = "SomeQueryString", ResponseFormat = System.ServiceModel.Web.WebMessageFormat.Json)]
public ParentClass GetCollection(parameter)
{
    ...
}