Ruby on Rails calling methods of objects

Question

There is something I don't understand about ruby.

@items.each do |item| 
  item.column
end

will work and return me the value for that column in rails. but

item = @items[some_item_id]
item.column

will give me a method not found exception for nil. Both times I get the object but only with the first I can access the rails data methodes.

What do those dashes |...| do and how do I access such methods?

Answer 1

This gathers all elements inside @items for passage into a block:

@items.each

#each will work on hashes, arrays, and other enumerables.

---

This selects a specific element inside @items:

@items[some_item_id]

The square brackets are a method (named #[]) for element reference in both hashes and arrays. If you get a MethodNotFound error, it means @items is not a hash or array and doesn't have a method named #[].

If @items is a collection of ActiveRecord objects and you want to select one by ID, use:

@items.find(some_item_id)