= merb-cache

A plugin for the Merb framework that provides caching

Currently supported methods:

- page caching:
- action caching
- fragment caching
- object caching

Implemented cache stores:

- memory
- memcache
- file
- database (sequel, datamapper, activerecord)

== Quick intro
  With fragment caching, you can mix dynamic and static content.

  With action caching, the whole template is cached
  but the before filters are still processed.

  With page caching, the whole template is put in html files in a special
  directory in order to be handled directly without triggering Merb.

== Quick API

=== Merb::Controller class methods
  cache_action(action, expiration)
  cache_actions(action, [action, expiration], ...)
  cache_page(action, expiration)
  cache_pages(action, [action, expiration], ...)

=== Merb::Controller instance methods
  expire_page(key)
  cached_page?(key)
  expire_all_pages()

  expire_action(key)
  cached_action?(key)

  cached?(key)
  cache_get(key)
  cache_set(key, data, expiration)
  expire(key)
  expire_all()

=== Inside your template
  cache(key, expiration) do ... end

  # expiration is given in minutes

  # key can be a string or a hash
  # possible keys when it's a hash:
  # :key (full key)
  # :params (array of params to be added to the key)
  # :action, :controller
  # :match (true or partial key)

  # Don't forget to look at the specs !!

== Specs
  $ rake specs:<cache_store>
  example:
  $ rake specs:memory
  $ rake specs:file
  or just:
  $ cd spec
  $ STORE=<cache_store> spec merb-cache_spec.rb
  # cache_store can be:
  #   memory, memcache, file, sequel, datamapper, activerecord

== Sample configuration

  Merb::Plugins.config[:merb_cache] = {
    :cache_html_directory => Merb.dir_for(:public) / "cache",

    #:store => "database",
    #:table_name => "merb_cache",

    #:disable => "development", # disable merb-cache in development
    #:disable => true, # disable merb-cache in all environments

    :store => "file",
    :cache_directory => Merb.root_path("tmp/cache"),

    #:store => "memcache",
    #:host => "127.0.0.1:11211",
    #:namespace => "merb_cache",
    #:no_tracking => false,

    #:store => "memory",
    # store could be: file, memcache, memory, database, dummy, ...
  }


== Quick Example

==== controller part
  class Users < Merb::Controller
    cache_page :action_name
    # this will cache the action in public/cache/something.html
    # this cache entry will never expire (no expiration provided)
    # for permanent caching you could set your lighty/nginx so as to handle
    # the .html file directly
    # for multiple page caching:
    # cache_pages :action_name, [:another_action, 5], :some_action

    cache_action :another_action, 10
    # this will cache the action using the cache store
    # this cache entry will expire in 10 minutes
    # for multiple action caching:
    # cache_actions :action_name, [:another_action, 5], :some_action

    def list
      unless @users = cache_get("active_users")
        @users = User.all(:active => true)
        cache_set("active_users", @users)
        # object caching can be used to avoid pulling huge amounts of data
        # from the database.
        # you could have calle cache_set with an expiration time as well:
        # cache_set("active_users", @users, 10)
      end
      render
    end

    def some_action_that_invalidates_cache
      expire_page(:action_name)
      expire_action(:another_action)
      render
    end

    def delete
      expire("active_users")
      render
    end

    def archives
      @archives = User.archives unless cached?("users_archives")
      render
    end

    def index
      render
    end
  end


====views/users/index.html.erb
  # this entry will expire in 10 minutes
  <%- cache "users_index", 10 do %>
   <div>some big template</div>
  <% end -%>

====views/users/archive.html.erb
  <%- cache "users_archives" do %>
   <div>some big template</div>
  <% end -%>