Object from database record

I have a problem with creating objects from database records. In the model Room I have declared instance variable (at the beginning of a class)

@exits = {:south=>nil, :north=>nil}

The database has been already populated with rooms.

Now, if somewhere in a program i use Room.find(1), I get the object room, however it doesn't see the @exists hash. How can I make it see it? I'm totally new to RoR and this being probably straightforward problem just drives me maaad. Help please.

I think not... Basically I want to have an instance variable, that is not related to any column from the database mapped to the object. And I want to be able to see that instance variable when creating the object through ModelName.find(id).