method

fresh_when

Ruby on Rails latest stable (v2.3.4) - 0 notes - Class: ActionController::Base

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What's this?

fresh_when(options) protected

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.

Show source

# File actionpack/lib/action_controller/base.rb, line 1187
      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]
        
        if options[:public] 
          cache_control = response.headers["Cache-Control"].split(",").map {|k| k.strip }
          cache_control.delete("private")
          cache_control.delete("no-cache")
          cache_control << "public"
          response.headers["Cache-Control"] = cache_control.join(', ')
        end

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

fresh_when

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