Abstract objects collection definition in wcf service

Question

I have in my DataContract a collection of objects defined as

Collection<BaseAbstractObject>

which I want to fill up with some inherited objects of type ClassA.

I'm using Soap UI to create such a request to my service method, but I'll get error "Cannot create an abstract class"

I have also decorated base class with [KnownType(ClassA)] attribute. My xml request looks like this:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:tem="http://tempuri.org/" xmlns:wcf="http://schemas.datacontract.org/2004/07/WcfService1" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
   <soapenv:Header/>
   <soapenv:Body>
      <tem:GetDataUsingDataContract>
         <tem:composite>
            <wcf:ClassesCollection>
               <wcf:BaseClass i:type="ClassA" >
                  <wcf:Id>1</wcf:Id>                      
                  <wcf:Name>ClassA</wcf:Name>
               </wcf:BaseClass>
            </wcf:ClassesCollection>
         </tem:composite>
      </tem:GetDataUsingDataContract>
   </soapenv:Body>
</soapenv:Envelope>

And this is how my DataContracts looks like:

[DataContract]
public class MyDataContract
{
    public MyDataContract()
    {
        ClassesCollection = new Collection<BaseClass>();
    }

    [DataMember]
    public Collection<BaseClass> ClassesCollection { get; private set; }
}

[DataContract]
[KnownType(typeof(ClassA))]
public abstract class BaseClass
{
    [DataMember]
    public int Id { get; set; }
}

[DataContract]
public class ClassA : BaseClass
{
    [DataMember]
    public int Name { get; set; }
}

So what should my request looks like? Or need I add some other attribute to DataContract?

Answer 1

First make sure that your collection has a public setter, otherwise WCF won't be able to deserialize it:

[DataMember]
public Collection<BaseClass> ClassesCollection { get; set; }

and then here's how a sample request might look like:

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body>
    <GetDataUsingDataContract xmlns="http://tempuri.org/">
      <composite xmlns:a="http://schemas.datacontract.org/2004/07/WcfService1" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
        <a:ClassesCollection>
          <a:BaseClass i:type="a:ClassA">
            <a:Id>1</a:Id>
            <a:Name>5</a:Name>
          </a:BaseClass>
        </a:ClassesCollection>
      </composite>
    </GetDataUsingDataContract>
  </s:Body>
</s:Envelope>