Question

I want to make a quick Ruby program that will allow me to read an XML file and sort a particular set of children, and then write it back sorted on disk. For example:

I want to sort from this XML file I made up:

<Nodes>
    <Node1>
        <Name>Fruits</Name>
        <Properties>
            <Property>
                <Name>Orange<Name>
            </Property>
            <Property>
                <Name>Vinegar<Name>
            </Property>
            <Property>
                <Name>Apple<Name>
            </Property>
        </Properties>
    </Node1>
    <Node2>
        <Name>Furniture</Name>
        <Properties>
            <Property>
                <Name>Table</Name>
            </Property>
            <Property>
                <Name>Desk</Name>
            </Property>
            <Property>
                <Name>Bed</Name>
            </Property>
        </Properties>
    </Node2>
</Nodes>

I want to sort the node Properties’s children alphabetically i.e.:

<Property>
    <Name>Apple<Name>
</Property>
<Property>
    <Name>Orange<Name>
</Property>
<Property>
    <Name>Vinegar<Name>
</Property>

Is there a way I can do this quickly with Ruby?

Answer 1

As you’re already aware from your choice of tags, your tool of choice will be Nokogiri. I had some issue parsing your XML so I rewrote it as following:

# sortnodes.xml
<nodes>
  <node1>
    <name>Fruits</name>
    <properties>
      <property>
        <name>Orange</name>
      </property>
      <property>
        <name>Vinegar</name>
      </property>
      <property>
        <name>Apple</name>
      </property>
    </properties>
  </node1>
  <node2>
    <name>Furniture</name>
    <properties>
      <property>
        <name>Table</name>
      </property>
      <property>
        <name>Desk</name>
      </property>
      <property>
        <name>Bed</name>
      </property>
    </properties>
  </node2>
</nodes>

And the corresponding code is:

require 'nokogiri'

f = File.open("sortnodes.xml")
doc = Nokogiri::XML(f)
f.close
doc.xpath('/nodes//properties').each do |properties| 
  sorted = properties.children.sort_by { |n| n.text }
  sorted.each { |n| properties << n } 
end