public IResult AddDeveloper(string developerName, string developerLastname, string username, List <int> categoryIds) { List <Category> categories = new List <Category>(); foreach (int categoryId in categoryIds) { Category cat = DbInstance.GetCategoryById(categoryId); categories.Add(cat); } Developer developer = new Developer { Categories = categories, CreatedDate = DateTime.Now, FirstName = developerName, LastName = developerLastname, UserName = username, }; try { DbInstance.AddDeveloper(developer); DbInstance.SaveChanges(); return(new SuccessResult(Messages.SuccessAddDeveloper)); } catch (Exception) { return(new ErrorResult(Messages.ErrorAddDeveloper)); } }