PesaPal OpenAuth integration (not working yet)

pesapal.rb

require 'oauth'
require 'uri'

key = # my Consumer Key (sandbox) 
sec = # my Consumer Secret (sandbox)

SITE_URL = 'https://demo.pesapal.com'

# An XML string of param data to include with our request
RAW_XML  = <<-XML
<?xml version=\"1.0\" encoding=\"utf-8\"?>
<PesapalDirectOrderInfo xmlns:xsi=\"http://www.w3.org/2001/XMLSchemainstance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" Amount=\"12.34\" Description=\"Bob Test 1\" Type=\"MERCHANT\" Reference=\"808\" FirstName=\"Bob\" LastName=\"Tester\" Email=\"[email protected]\" xmlns=\"http://www.pesapal.com\" />
XML

# Escape the XML
@post_xml = URI.escape(RAW_XML)

# Create a new OAuth Consumer
@consumer = OAuth::Consumer.new(key, sec, {
  site: SITE_URL, 
  scheme: :query_string
})
# The signed request object
@signed_request  = @consumer.create_signed_request('get', "/API/PostPesapalDirectOrderV4")

# Join the pesapal_request_data and oauth_callback with '&' for valid URL params
@params = { 
  oauth_callback: URI.escape('http://localhost:3000'),
  pesapal_request_data: @post_xml,
}.map { |k,v| "#{k}=#{v}" }.join('&')

# This is the URL we should redirect to
redirect_url = "#{SITE_URL}/#{@signed_request.path}&#{@params}"

If anyone else finds themselves here ... you could try the pesapal gem (works and has been production ready since 2014). See releases for details.