using System;

using System.Collections.Generic;

public interface EntityRepository

{

    //IEnumerable<BaseEntity> GetAll();

    BaseEntity GetById(int Id);

    //BaseEntity Insert(BaseEntity entity);

    //BaseEntity Update(BaseEntity entity);

    //void Delete(int Id);

}

​

public class CourseRepository : EntityRepository

{

    public BaseEntity GetById(int Id)

    {

        return new Course {Title = "Title", Description="descr", Price = 0, CategoryId = 1};           

    }

}

​

public class Program

{

    public static void Main()

    {

        CourseRepository cr = new CourseRepository();

        Console.WriteLine("{0}, {1}, {2}", ((Course)cr.GetById(1)).Title, ((Course)cr.GetById(1)).Description, ((Course)cr.GetById(1)).Price);

    }

}

​

​

public class BaseEntity

{

        public int Id { get; set; }

}

​

public class Course : BaseEntity

{

    public string Title { get; set; }

    public string Description { get; set; }

    public decimal? Price { get; set; }

    public int CategoryId { get; set; }

}