Question

I’m struggling to define a class method that populates and returns a collection of instances. The issue I don’t know how to get around is that I have private attributes to populate.

Let’s use the example of a Book class. I don’t want the code to directly set (say) the availability of a book. I want the code to have to use a CheckOut method on a Book instance. So we have something like:

public class Book {   private int ID;   private bool pAvailableForCheckout;    public string Title { get; set; }   public bool AvailableForCheckout { get { return pAvailableForCheckout } }    // instance methods    public Book(int BookID)   {      // Load book from DB by ID   }   public CheckOut()   {      // perform everything involved with checking a book out   }   // .. other methods like saving a book, checking out books etc.    // class method    public static List<Book> FindAll()   {      // load Dataset of books      // foreach record in DB, use the Book(int BookID) constructor and add to List      // return list of books   } } 

So, I can do use this in my code:

foreach(Book curBook in Book.FindAll())   { /* do something with book */ } 

The problem with the above implementation is that I have to use N+1 hits to the database to load all the books instead of just 1 query. How do I get around this?

I’m sure this is programming 101, but I needed to ask.

Answer 1

You could create a protected constructor which populates the private properties directly.