Fragment caching

Rails.cache, provided by ActiveSupport, can be used to cache any serializable Ruby object across requests.

To fetch a value from the cache for a given key, use cache.read:

Rails.cache.read('city')
# => nil

Use cache.write to write a value to the cache:

Rails.cache.write('city', 'Duckburgh')
Rails.cache.read('city')
# => 'Duckburgh'

Alternatively, use cache.fetch to read a value from the cache and optionally write a default if there is no value:

Rails.cache.fetch('user') do
  User.where(:is_awesome => true)
end

The return value of the passed block will be assigned to the cache under the given key, and then returned.

You can also specify a cache expiry:

Rails.cache.fetch('user', :expires_in => 30.minutes) do
  User.where(:is_awesome => true)
end