Question

I have an object that’s being automatically serialized by the WebAPI, but I wanted to wrap it to provide context to my data. An example would be:

public class SecureModel<T>
{
  public string Info { get; set; }
  public T Data { get; set; }
}

This serializes/deserializes no problem with my JSON requests and all is well. However, I want to verify some of that Info before I allow the request to finish executing, so I’ve added an ActionFilter where I’m retrieving parameters of my POST.

public class MyAuth : System.Web.Http.Filters.ActionFilterAttribute
{
  public override void OnActionExecuting(HttpActionContext actionContext)
  {
    var arg = actionContext.ActionArguments.FirstOrDefault().Value;
    // arg: get the Info?
    // if the info isn't correct, return a specific Response.
  }
}

When I examine the argument, it’s exactly what I need, however I can’t figure out how to weakly type it to SecureModel without specifying the actual generic type. I feel like I should be able to case this to SecureModel<object> and properly access the root, however it does not allow that. So far, I can only get the data I need using:

var notStrongEnough = arg.GetType().GetProperty("Info");

However, I’d prefer not to use Reflection for this and I am having a hard time moving forward without an answer. My alternative in this situation would be to change Data to a string and serialize/deserialize the JSON object manually, but that defeats some of the purpose of using Web API over MVC3.

Note: Changing the design to have SecureModel as the base class adds challenges to some of the hashing I am performing on the data, so I’d prefer to not go down that path either.

Thanks!

Edit: Misphrased title.

Answer 1

The typical solution to this sort of problem in C# is to create non-generic interfaces that your generic types implement. For example, with your class:

public class SecureModel<T>
{
    public string Info { get; set; }
    public T Data { get; set; }
}

You could define an interface, ISecureModel:

public interface ISecureModel 
{
    string Info { get; }
    object Data { get; }
}

And now you can implement it in your data class:

public class SecureModel<T> : ISecureModel
{
    public string Info { get; set; }
    public T Data { get; set; }

    object ISecureModel.Data {
        get { return Data; }
    }
}

We use explicit interface implementation here since the non-generic (object) and generic (T) versions of property Data would otherwise collide.

Now, to get the info, you can simply cast to ISecureModel.