mikedemers / caching-mailer

A Rails plug-in that enables fragment caching in ActionMailer templates

= CachingMailer

Enables the use of fragment caching in ActionMailer views.

Shares the cache configuration of ActionController::Base.


== Resources

* Source: http://github.com/mikedemers/caching-mailer/tree/master
* Support: http://github.com/mikedemers/caching-mailer/issues


== Installation

  script/plugin install git://github.com/mikedemers/caching-mailer.git


== Usage

Configure fragment caching in "config/environment.rb" (or in the
configuration file for a specific environment such as
"config/environments/production.rb"):

  config.action_controller.perform_caching = true
  config.cache_store = :file_store, File.join(Rails.root, 'tmp', 'cache')


For the mailer "app/models/hello_mailer.rb":

  class HelloMailer < ActionMailer::Base
    
    include_fragment_caching
    
    def hello
      subject     "Hello, World"
      recipients  "[e-mail]"
      from        "[e-mail]"
      sent_on     Time.now
    end
  end

And the template "app/views/hello_mailer/hello.text.plain.erb":

  Hello, World!
  
  This is an computationally expensive list:
  
  <% cache("mail/expensive-list") do %>
     <% ExpensiveOperation.results.each do |result| %>
     * Item #<%= result.id %>: "<%= result.title %>"
     <% end %>
  <% end %>

The computationally expensive method `ExpensiveOperation.results` will only
be invoked once.  Subsequent emails will use the cached result.

For automatic expiration, try including a time value in the cache key.  This
example will generate a new cache entry every 2 hours (removal of stale
entries is left as an exercise to the reader):

  <% cache("mail/expensive-list-#{Time.now.to_i / 2.hours.to_i}") do %>
     <% ExpensiveOperation.results.each do |result| %>
     * Item #<%= result.id %>: "<%= result.title %>"
     <% end %>
  <% end %>


Copyright (c) 2009 Mike Demers <mike_(at)_9astronauts.com>, released under
the MIT license.