Error using Xpath in Rhomobile - rhomobile

Question

I am trying to parse XML using rexml Xpath, but facing error as const_missing: XPath in rhomobile application. can anyone give me the solution.
Below is the sample code:
file = File.new(file_name)
begin
require 'rexml/document'
xmldoc = REXML::Document.new(file)
names = XPath.match(xmldoc, "//MP_HOST_NAME" )

Answer 1

in your build.yml file:
extensions:
- rexml
if using blackberry, replace rexml with rhoxml
Assuming you've done this, replace your XPath with:
REXML::XPath.match(xmldoc, "//MP_HOST_NAME" )

Answer 2

Here is a sample controller I knocked to test xml parsing
I can use the get_names method in the view then to get an array of names
require 'rho/rhocontroller'
require 'rexml/document'
class WebServiceTestController < Rho::RhoController
def index
##get_result = ""
Rho::AsyncHttp.get(
:url => 'http://www.somesite.com/some_names.xml',
#:authorization => {:type => :basic, :username => 'user', :password => 'none'},
:callback => (url_for :action => :httpget_callback),
:authentication => {
:type => :basic,
:username => "xxxx",
:password => "xxxx"
},
:callback_param => "" )
render :action => :wait
end
def get_res
##get_result
end
def get_error
##error_params
end
def httpget_callback
if #params["status"] != "ok"
##error_params = #params
WebView.navigate( url_for(:action => :show_error) )
else
##get_result = #params["body"]
begin
# require "rexml/document"
##doc = REXML::Document.new(##get_result)
# puts "doc : #{doc}"
rescue Exception => e
# puts "Error: #{e}"
##get_result = "Error: #{e}"
end
WebView.navigate( url_for(:action => :show_result) )
end
end
def show_error
render :action => :error, :back => '/app'
end
def show_result
render :action => :index, :back => "/app"
end
def get_doc
##doc
end
def get_names
names = []
REXML::XPath.each( get_doc, "//name_or_whatever_you_are_looking_for") do |element|
names << element.text
end
names
end
end
ensure that rhoxml is set in the build.yml file rather than rexml this works fine and it's a little faster