Using cookies to store and retrieve
At it's simplest, a cookie collection object needs to do the following.Add items
Retrieve all items
In this example, I want to be able to show a list of recent restaurants on the side of the page.
Do do this, I would like an interface that allows me to add a recent restaurant.
recent_restaurants.push(@restaurant)
Or, to retrieve recent restaurants...
recent_restaurants
I'd like to avoid making direct calls using the 'cookies' hash, instead interact with the collection and hold the list between requests in the cookie.
With a CookieCollection class, we can use this to handle the common additions and deletes. We also get all the power that comes with the Array class. This class is meant to be subclassed.
class CookieCollection < Array
attr_accessor :ids
def initialize(cookies)
super(0)
@_cookies = cookies
if @_cookies[cookie_name].present?
self.ids = @_cookies[cookie_name].split(',')
else
self.ids = []
end
end
def push(object)
super(object)
update_cookie
end
private
def update_cookie
ids = map(&:id)
@_cookies[cookie_name] = {:value => ids.join(','), :expires => 20.years.from_now}
end
def cookie_name
self.class.name.parameterize
end
end
Note - the cookie value is only the ids of the object.
In a RecentRestaurants subclass, we can make the specific updates to our list of recent restaurants. In this case, I wanted to limit my list to the last 5 items.
class RecentRestaurants < CookieCollection
def initialize(cookies)
super(cookies)
self.ids = ids.last(5)
ids.each{ |r_id| push(Restaurant.find(r_id)) }
end
def push(restaurant)
delete(restaurant)
while length > 4
delete_at(0)
end
super(restaurant)
end
end
In the application controller, I exposed a helper method to allow access to recent_restaurants
def recent_restaurants
@_recent_restaurants ||= RecentRestaurants.new(cookies)
end
helper_method :recent_restaurants
And then, in a view or controller, you can easily do things like
class RestaurantsController < ApplicationController
def show
@restaurant = Restaurant.find(params[:id])
# Add a restaurant
recent_restaurants.push(@restaurant)
# Access all recent restaurants easily
recent_restaurants
end
end
This cleans things up quite a bit and makes it easier to work with in a consistent way. It could easily be extended to be used with Sessions, as well.
