I have an abstract base class with generics, I will simplify it for this question:
public abstract class DBBaseTable<T>
{
public T Id { get; set; }
public byte[] RowVersion { get; set; }
}
Now, I can have classes like: Person : DBBaseTable<int>
or Animal: DBBaseTable<Guid>
I am trying to avoid reflection in order to access the property RowVersion in a part of the code where I simply do not know the T
Type.
var memberInfo = oldObject.GetType().BaseType;
if (memberInfo != null
&& memberInfo.IsGenericType
&& memberInfo.GetGenericTypeDefinition() == typeof(DBBaseTable<>)
)
{
var isCorrectRowVersion = (oldObject as DBBaseTable<object>).RowVersion ==
(objToUpdate as DBBaseTable<object>).RowVersion;
//TODO....
}
The conditional IF condition is working fine... but then when I try to use the as
operator I always need to specify the T
type... I have tried to use "object" but it is not working... and I simply do not know if I am dealing with int, guid or some other type....
I know how to solve this with reflection, but I would like to know if there is an alternative?
Move the RowVersion
into a base class.
public abstract DBBaseTable
{
public byte[] RowVersion { get; set; }
}
public abstract class DBBaseTable<T> : DBBaseTable
{
public T Id { get; set; }
}
Another option is to declare a base interface with RowVersion
property and implement it in DBBaseTable<T>
base class
public interface IDBTable
{
byte[] RowVersion { get; set; }
}
public abstract class DBBaseTable<T> : IDBTable
{
public T Id { get; set; }
public byte[] RowVersion { get; set; }
}
public class Person : DBBaseTable<int>
{
//rest of logic
}
Then you can access a RowVersion
property without a cast
var isCorrectRowVersion = oldObject.RowVersion == objToUpdate.RowVersion;
With interfaces you are allowed to use covariance and contravariance in generic types.
Also, you can implement multiple interfaces in one class, but inherit only one base class in DBBaseTable<T>
. If you'll need to extend it in future, using an interface is preferable, IMO. But final decision depends on your needs.
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