C# casting an object within lambda

Question

I am currently trying to set a field which I need in business logic which in this case is Lazy. (yes not the property, it is necessary to set the field) I get the error that Lazy can not be converted to Lazy as you can see:

Object of type 'BusinessLogic.Lazy1[System.Object]' cannot be converted to type 'BusinessLogic.Lazy1[BusinessLogic.ArtikelBLL]

I use this line to get a dynamic repository.

dynamic repository = Activator.CreateInstance(typeof(GenericRepository<>).MakeGenericType(typeArgs));

Then I try to set the value of the field but it fails:

fInfo.SetValue(obj, Lazy.From(() => repository.GetDataById(id)));

I have tried to solve it many different ways. Somehow I have to cast repository.GetDataById(id) to the Entity it is looking for, which in this case is ArtikelBLL (which i can get through pInfo.PropertyType). But by doing (ArtikelBLL)repository.GetDataById(id) it will not remain object orientated. Can anybody please help me with this?

Answer 1

The simplest way would be to just use a cast inside the lambda:

fInfo.SetValue(obj, new Lazy<GenericBLL>(
    () => (ArtikelBLL) repository.GetDataById(id)));

After all, that's the type the Lazy<T> wants.

EDIT: If you're trying to do this dynamically, I suggest you write a generic method like this:

public Lazy<T> CreateLazyDataFetcher<T>(dynamic repository)
{
    return new Lazy<T>(() => (T) repository.GetDataById(id));
}

Then call that method with reflection. (Using MethodInfo.MakeGenericMethod(...).Invoke(...))