Convert generic list of class A and B with same properties to List of class C using generics

Question

I have 3 classes, DOb, Patient, and LookUp

public class Dog
    {  public int Id { get; set; }
        public DateTime DOB { get; set; }
        public string FirstName { get; set; }
        public string Display { get; set; }
        public int qqQMS { get; set; }
        public string Description { get; set; }
    }

public class Patient
    {
       public int Id { get; set; }
        public Guid Patid { get; set; }
        public string FirstName { get; set; }
        public string Display { get; set; }
        public string Description { get; set; }
    }
 public class LookUp : ILookUp
        public int Id { get; set; }
        public string Display { get; set; }
        public string Description { get; set; }
    }

I am trying to easily take a list or List convert it to List I asked this question before and never figured it out, with out using a Dynamic, I would rather have a smoother way without Dynamics

I have tried

 List<LookUp> Look = doggy.Cast<LookUp>().ToList();

  List<LookUp> patLook = pat.Cast<LookUp>().ToList();

also tried this but I am not happy with it

public static IList<LookUp> ToLookUp<T>( IEnumerable<T> source)  
        {
            List<LookUp> list = (from prop in source
                                 select new LookUp
                                 {
                                     Display = prop.Display ?? "",
                                     Description = prop.Description ?? "",
                                     Id = prop.Id
                                 }).ToList();
            return list;
        }

an extension method could work

Answer 1

You will need to implement the interface on your classes , the concrete Lookup class is not needed at this point:

public class Dog : ILookUp { ... }

public class Patient : ILookUp { ... }

That way you can cast to your interface and use it:

var listOfDogs = new List<dog>();

var LookupList = listOfDogs.Cast<ILookup>();

---

I would love to but Dob ad Patient are created else where and I cannot modify them

Then there is no easier way to do this, you can't really make a generic solution without reflection, you will have to project to Lookup as you are doing, or make an expression for each type.