Using OmniXML and Delphi, how do I locate an element by its attribute and change another element in node?

Question

Using OmniXML and Delphi, I would like to locate an element and change another element in the node. For example, in the xml listing below, I would like to locate /first-name = 'Joe1' and then locate and change the /price from 1200 to 10. I've tried using XPathSelect but I can not seem to specify the /first-name.

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="myfile.xsl" ?>
<bookstore specialty="novel">
  <book style="autobiography">
    <author>
      <first-name>Joe1</first-name>
      <last-name>Bob</last-name>
      <award>Trenton Literary Review Honorable Mention</award>
    </author>
    <price>1200</price>
  </book>
  <book style="textbook">
    <author>
      <first-name>Mary</first-name>
      <last-name>Bob</last-name>
      <publication>Selected Short Stories of
        <first-name>Mary</first-name>
        <last-name>Bob</last-name>
      </publication>
    </author>
    <editor>
      <first-name>Britney</first-name>
      <last-name>Bob</last-name>
    </editor>
    <price>55</price>
  </book>
</bookstore>

Answer 1

Use //book[author/first-name = "Joe1" ] as your XPathSelect query to get the node, and then access the subnode Price from that node to change it.