app/concerns/liquid_interpolatable.rb

@@ -43,12 +43,29 @@ module LiquidInterpolatable

                   end
              

                 
              

                   require 'uri'
              

                -  # Percent encoding for URI conforming to RFC 3986.
              

                -  # Ref: http://tools.ietf.org/html/rfc3986#page-12
              

                   module Filters
              

                +    # Percent encoding for URI conforming to RFC 3986.
              

                +    # Ref: http://tools.ietf.org/html/rfc3986#page-12
              

                     def uri_escape(string)
              

                       CGI.escape(string) rescue string
              

                     end
              

                +
              

                +    # Escape a string for use in XPath expression
              

                +    def to_xpath(string)
              

                +      subs = string.scan(/\G(?:\A\z|[^"]+|[^']+)/).map { |x|
              

                +        case x
              

                +        when /"/
              

                +          %Q{'#{x}'}
              

                +        else
              

                +          %Q{"#{x}"}
              

                +        end
              

                +      }
              

                +      if subs.size == 1
              

                +        subs.first
              

                +      else
              

                +        'concat(' << subs.join(', ') << ')'
              

                +      end
              

                +    end
              

                   end
              

                   Liquid::Template.register_filter(LiquidInterpolatable::Filters)
              

                 
              

spec/concerns/liquid_interpolatable_spec.rb

@@ -1,4 +1,5 @@

                 require 'spec_helper'
              

                +require 'nokogiri'
              

                 
              

                 describe LiquidInterpolatable::Filters do
              

                   before do
              
@@ -36,4 +37,21 @@ describe LiquidInterpolatable::Filters do

                       agent.errors[:options].first.should =~ /not properly terminated/
              

                     end
              

                   end
              

                +
              

                +  describe 'to_xpath' do
              

                +    before do
              

                +      def @filter.to_xpath_roundtrip(string)
              

                +        Nokogiri::XML('').xpath(to_xpath(string))
              

                +      end
              

                +    end
              

                +
              

                +    it 'should escape a string for use in XPath expression' do
              

                +      [
              

                +        %q{abc}.freeze,
              

                +        %q{'a"bc'dfa""fds''fa}.freeze,
              

                +      ].each { |string|
              

                +        @filter.to_xpath_roundtrip(string).should == string
              

                +      }
              

                +    end
              

                +  end
              

                 end
              

spec/models/agents/website_agent_spec.rb

@@ -456,7 +456,10 @@ fire: hot

                       before do
              

                         @event = Event.new
              

                         @event.agent = agents(:bob_rain_notifier_agent)
              

                -        @event.payload = { 'url' => "http://xkcd.com" }
              

                +        @event.payload = {
              

                +          'url' => 'http://xkcd.com',
              

                +          'link' => 'Random',
              

                +        }
              

                       end
              

                 
              

                       it "should scrape from the url element in incoming event payload" do
              
@@ -467,17 +470,25 @@ fire: hot

                       end
              

                 
              

                       it "should interpolate values from incoming event payload" do
              

                -        @event.payload['title'] = 'XKCD'
              

                -
              

                         lambda {
              

                -          @valid_options['extract']['site_title'] = {
              

                -            'css' => "#comic img", 'value' => "'{{title}}'"
              

                +          @valid_options['extract'] = {
              

                +            'from' => {
              

                +              'xpath' => '*[1]',
              

                +              'value' => '{{url | to_xpath}}'
              

                +            },
              

                +            'to' => {
              

                +              'xpath' => '(//a[@href and text()={{link | to_xpath}}])[1]',
              

                +              'value' => '@href'
              

                +            },
              

                           }
              

                           @checker.options = @valid_options
              

                           @checker.receive([@event])
              

                         }.should change { Event.count }.by(1)
              

                 
              

                -        Event.last.payload['site_title'].should == 'XKCD'
              

                +        Event.last.payload.should == {
              

                +          'from' => 'http://xkcd.com',
              

                +          'to' => 'http://dynamic.xkcd.com/random/comic/',
              

                +        }
              

                       end
              

                     end
              

                   end