Rails 2.3 allows you to set the Expires header using the expires_in method. However this couples your caching strategy with your controller code. And it spreads out the caching configuration all over the place. This plugin allows you to keep your caching configuration in one place out of the controllers.

Install

Install as a gem (gem install expiry_control) and add it in your environmen.rb file.

Usage

Create a file somewhere, maybe in config/initializers that will contain your configuration. The name doesn't matter. Your configuration will go into the following block of code:

ExpiryControl.configure do |config|
  # configuration goes here
end

Just like when you configure your routes you call methods on the object passed into the block:

# Set Expires header to 1 hour for the whole blog controller
config.cache "blog", :for => 1.hour

# Set Expires header to 5 minutes for a special action, this overrides
# the controller wide setting
config.cache "blog#special", :for => 5.minutes

# Set a default caching time
config.default 1.minute

This is all there is to it for the basic usage. Note that more specialized rules take precedence. Specifically, the code first looks for a rule at the action level (or rather action in a specific controller), then at the controller level and the it uses the default rule (if it exists).

Sometimes however this is not enough and you need to make the caching optional. For these cases you can use :if and :unless like you would use in validations. Note, that you have to use a Proc symbols or strings are not supported. This Proc gets passed the controller object for maximum flexibility.

# Only cache if 'cache' param is set
config.cache "blog", :for => 1.hour, :if => Proc.new {|controller| controller.params["cache"]}