Method: ActionController::ConditionalGet#fresh_when

Defined in:
lib/action_controller/metal/conditional_get.rb

#fresh_when(options) ⇒ Object

Sets the etag, last_modified, or both on the response and renders a “304 Not Modified” response if the request is already fresh.

Parameters:

  • :etag

  • :last_modified

  • :public By default the Cache-Control header is private, set this to true if you want your application to be cachable by other devices (proxy caches).

Example:

def show
  @article = Article.find(params[:id])
  fresh_when(:etag => @article, :last_modified => @article.created_at.utc, :public => true)
end

This will render the show template if the request isn’t sending a matching etag or If-Modified-Since header and just a “304 Not Modified” response if there’s a match.


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# File 'lib/action_controller/metal/conditional_get.rb', line 26

def fresh_when(options)
  options.assert_valid_keys(:etag, :last_modified, :public)

  response.etag          = options[:etag]          if options[:etag]
  response.last_modified = options[:last_modified] if options[:last_modified]
  response.cache_control[:public] = true if options[:public]

  head :not_modified if request.fresh?(response)
end