CODEWITHSUNDEEP
c#web-servicesrestasp.net-web-apiget
DasDave
DasDave

Reputation: 811

HTTP Get return multiple types

I'm writing a web service and I am attempting to add a response to a Get request. The difficulty is, I have multiple types that need to be returned. So initially I have a base class of:

public abstract class AbstractSource
{
    public string name { get; set; }
}

followed by two derivatives:

public class DatabaseSource : AbstractSource
{
}

and 

public class WebSource : AbstractSource
{

}

These classes will eventually have more of their own specific elements. In my controller class I have the following test code:

public class DataSourcesController : ApiController
{
    AbstractSource[] sources = new AbstractSource[] 
    { 
        new WebSource { name="WebPath"},
        new DatabaseSource{name="DB Source"}
    };

    public IEnumerable<AbstractSource> GetAllDataSources()
    {
        return sources;
    }
}

Now when I run this I get a serializationException. Is it even possible to return mulitple types like this?

Upvotes: 0

Views: 488

Answers (1)

Maggie Ying
Maggie Ying

Reputation: 10175

Sounded like you are trying to use get the data in XML.

The XML Serializer (e.g. the DataContractSerializer) doesn't know how to deserialize AbstractSource into either DatabaseSource or WebSource, and so you will need to snap the [KnownType(...)] attributes on your AbstractSource class:

using System.Runtime.Serialization;

[KnownType(typeof(DatabaseSource))]
[KnownType(typeof(WebSource))]
public abstract class AbstractSource
{
    public string name { get; set; }
}

Upvotes: 2

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