Lesson: make terms that reference attributes on xml elements

This Tutorial is known to work with om version 3.0.4.
Please update this wiki to reflect any other versions that have been tested.

Goals

• Define Terms in a Terminology that refer to XML attribute values rather than referring to the text within XML elements

Explanation

Steps

Step 1: Think about what the XML is going to look like

Now say we want to use the xml:lang attribute to track the language encoding of the title and we want to have an OM Term called title_language that lets us read and modify that attribute's value.

<fields>
  <title lang="eng">ZOIA! Memoirs of Zoia Horn, Battler for the People's Right to Know.</title>
</fields>

Step 2: Define the Term in your Terminology

Reopen fancy_book_metadata.rb and add a language nested inside the title Term

    t.title {
      t.language(path: { attribute: "lang" })
    }

Step 3: Try modifying an OM Document based on the Terminology

Restart the console

bundle console

Require the FancyBookMetadata class definition.

require "./fancy_book_metadata"
fancybook = FancyBookMetadata.new

fancybook.title = "Zoia!"
 => "Zoia!" 
fancybook.title.language = "eng"
puts fancybook.to_xml
<?xml version="1.0"?>
<fields>
  <title lang="eng">Zoia!</title>
</fields>
 => nil 

Next Step

Go on to Lesson: Make Terms that reference XML elements with certain attribute values or return to the Tame your XML with OM page.