Nokogiri: parse and update value in Plist - ruby

Question

I'm new to Ruby and need to process some plist for a book store, say if I have a plist of books,
<plist>
<array>
<dict>
<key>Name</key>
<string>An Old Man and the Sea</string>
<key>Available</key>
<true/>
</dict>
<dict>
<key>Name</key>
<string>The Hitchhiker's Guide To Galaxy</string>
<key>Available</key>
<false/>
</dict>
</array>
</plist>
I need to switch the availability of books, and I have read the plist and parsed the array of books into books:
books.map do |book|
book.xpath("key/text()") # e.g. ["Name", "Available"]
book.xpath("string/text()") # e.g. ["An Old Man and the Sea"]
end
Questions:
How do I read the value <true/> and <false/>?
How do I update the value and save the plist?
Thanks!

Answer 1

If you don't mind using a gem, there is plist_lite.
ruby -r plist_lite -e 'p PlistLite.load($stdin.read)' <<EOS
<plist>
<array>
<dict>
<key>Name</key>
<string>An Old Man and the Sea</string>
<key>Available</key>
<true/>
</dict>
<dict>
<key>Name</key>
<string>The Hitchhiker's Guide To Galaxy</string>
<key>Available</key>
<false/>
</dict>
</array>
</plist>
EOS
output:
[{"Name"=>"An Old Man and the Sea", "Available"=>true},
{"Name"=>"The Hitchhiker's Guide To Galaxy", "Available"=>false}]
If you want to do it yourself with nokogiri, you can refer to plist_lite's source code here, it also uses nokogiri:
https://github.com/tonytonyjan/plist_lite/blob/2de0506/lib/plist_lite.rb#L37-L57
To answer your question:
How do I read the value <true/> and <false/>?
parsed = PlistLite.load(plist_string)
parsed.map{ _1['Available'] }
How do I update the value and save the plist?
parsed = PlistLite.load(plist_string)
parsed.first['Available']
IO.write 'test.plist', PlistLite.dump(parsed)