Discussion on: What's the best way to render specific items from a Rails collection?

What about...

In the controller:

@cocktails = Cocktail.for_sale.to_a # for_sale scope or whatever, solidified as Array.

Helper:

def cocktail(cocktails, name)
  cocktails.select { |c| c.name == name }.first
end

This way you select from the array each time.

If you really want to make the query maximally efficient, you could use pluck which would return an array of arrays containing the values you need. So...

In the controller:

@cocktails = Cocktail.for_sale.pluck(:name, :description, :price) # @cocktails[0] would look like ["margarita", "Good drink", 9] or whatever.

Helper:

def cocktail(cocktails, name)
  cocktails.select { |c| c[0] == name }.first
end

I might be offbase in how I'm thinking about this, but at least it might help you look up some of these methods for use now and/or future.