Casting an object using the “as” keyword returns null

Question

Here are my classes definitions:

public abstract class AbstractEntity : ...
public partial class AbstractContactEntity : AbstractEntity, ...
public sealed cl         


        

Answer 1

They are not the same types. It is the same as with List<string> and List<int>: They also can't be casted to one another. That AbstractContactEntity is a AbstractEntity doesn't change this. Extracting an interface from EntityCollectionProxy<T> and making it covariant doesn't work either, because you want to implement IList<T> which means you have input paramaters and return values of type T which prevents covariance.

The only possible solution is the following:

var tmp = (EntityCollectionProxy<AbstractContactEntity>)obj;
var col = tmp.Select(x => (AbstractEntity)x);

col will be of type IEnumerable<AbstractEntity>. If you want to have a EntityCollectionProxy<AbstractEntity>, you need to create a new one:

var result = new EntityCollectionProxy<AbstractEntity>(col);

This assumes that your EntityCollectionProxy<T> class has a constructor that accepts an IEnumerable<T>.
But beware, this will be a NEW instance and not the same as returned by resolver.DynamikInvoke.