xml = %{
<freezer temp="-12" scale="celcius">
 <food>Phyllo dough</food>
 <food>Ice cream</food>
 <icecubetray>
  <cube1 />
  <cube2 />
 </icecubetray>
</freezer>}
require 'rubygems'
require 'xmlsimple'
doc = XmlSimple.xml_in xml
require 'pp'
pp doc

{"icecubetray"=>[{"cube2"=>[{}], "cube1"=>[{}]}],
"food"=>["Phyllo dough", "Ice cream"],
"scale"=>"celcius",
"temp"=>"-12"}

{"icecubetray"=>[{"cube2"=>[{}], "cube1"=>[{}]}],
 "food"=>["Phyllo dough", "Ice cream"],
 "scale"=>"celcius",
 "temp"=>"-12"}

xml = %{
<freezer temp="-12" scale="celcius">
 <item name="Phyllo dough" type="food" />
 <item name="Ice cream" type="food" />
 <item name="Ice cube tray" type="container">
  <item name="Ice cube" type="food" />
  <item name="Ice cube" type="food" />
 </item>
</freezer>}
parsed1 = XmlSimple.xml_in xml
pp parsed1

{"scale"=>"celcius",
"item"=>
[{"name"=>"Phyllo dough", "type"=>"food"},
{"name"=>"Ice cream", "type"=>"food"},
{"name"=>"Ice cube tray",
"type"=>"container",
"item"=>
[{"name"=>"Ice cube", "type"=>"food"},
{"name"=>"Ice cube", "type"=>"food"}]}],
"temp"=>"-12"}

{"scale"=>"celcius",
 "item"=>
  [{"name"=>"Phyllo dough", "type"=>"food"},
   {"name"=>"Ice cream", "type"=>"food"},
   {"name"=>"Ice cube tray",
    "type"=>"container",
    "item"=>
     [{"name"=>"Ice cube", "type"=>"food"},
      {"name"=>"Ice cube", "type"=>"food"}]}],
 "temp"=>"-12"}

parsed2 = XmlSimple.xml_in(xml, 'KeyAttr' => 'name')
pp parsed2

{"scale"=>"celcius",
"item"=>
{"Phyllo dough"=>{"type"=>"food"},
"Ice cube tray"=>
{"type"=>"container",
"item"=>{"Ice cube"=>{"type"=>"food"}}},
"Ice cream"=>{"type"=>"food"}},
"temp"=>"-12"}

{"scale"=>"celcius",
 "item"=>
  {"Phyllo dough"=>{"type"=>"food"},
   "Ice cube tray"=>
    {"type"=>"container", "item"=>{"Ice cube"=>{"type"=>"food"}}},
   "Ice cream"=>{"type"=>"food"}},
 "temp"=>"-12"}

parsed1["item"].detect { |i| i['name'] == 'Phyllo dough' }['type']

parsed2["item"]["Phyllo dough"]["type"]

parsed1["item"] << {"name"=>"Curry leaves", "type"=>"spice"}
parsed1["item"].delete_if { |i| i["name"] == "Ice cube tray" }
puts XmlSimple.xml_out(parsed1, "RootName"=>"freezer")

<freezer scale="celcius" temp="-12">
<item name="Phyllo dough" type="food" />
<item name="Ice cream" type="food" />
<item name="Curry leaves" type="spice" />
</freezer>

<freezer scale="celcius" temp="-12">
  <item name="Phyllo dough" type="food" />
  <item name="Ice cream" type="food" />
  <item name="Curry leaves" type="spice" />
</freezer>

parsed3 = XmlSimple.xml_in(xml, 'KeepRoot'=>true)

Now there's no need to add an extra root element when writing back to XML.

XmlSimple.xml_out(parsed3, 'RootName'=>nil)
pp XmlSimple.xml_in(%{
<freezer temp="-12" scale="celcius">
 <temp>Body of temporary worker who knew too much</temp>
</freezer>})

{"scale"=>"celcius",
"temp"=>["-12", "Body of temp worker who knew too much"]}

{"scale"=>"celcius",
 "temp"=>["-12", "Body of temporary worker who knew too much"]}