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Caching Mailer

Enables the use of fragment caching in ActionMailer views.

Shares the cache configuration of ActionController::Base.

Resources

• Source: http://github.com/mikedemers/caching-mailer
• 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  "you@foo.com"
    from        "me@bar.com"
    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 %>