Nokogiri for reading and editing Plist - ruby

Question

I need to read and edit part of a plist file, it looks like:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Bookstore</key>
<dict>
<key>Public</key>
<dict>
<key>Books</key>
<array>
<dict>
<key>Name</key>
<string>The Old Man and the Sea</string>
<key>Author</key>
<string>Hemingway</string>
</dict>
<dict>
<key>Name</key>
<string>A Brief History of Time</string>
<key>Author</key>
<string>Stephen Hawkin</string>
</dict>
</array>
</dict>
</dict>
</dict>
</plist>
What I've done so far:
require 'nokogiri'
doc = doc = Nokogiri::XML(File.open("books.plist"))
doc.xpath("//dict[key=\"Bookstore\"]/dict[key=\"Public\"]/dict[key=\"Books\"]")
If I want to get an array of hashes (in Ruby) of elements under "Book", what should I do next?
Thanks!

Answer 1

I think you can expand your selection to grab exactly the elements you need:
require 'nokogiri'
doc = Nokogiri::XML(File.open("books.plist"))
books = doc.xpath("//dict[key='Bookstore']/dict[key='Public']/dict[key='Books']/array/dict")
Then you can convert this array of book elements into the shape you want by sub-selecting, or traversing, but sub-selecting might look like this:
final = books.map do |book|
keys = book.xpath("key/text()").map(&:to_s)
values = book.xpath("string/text()").map(&:to_s)
Hash[keys.zip(values)]
end

Answer 2

You can use Ruby gems like plist_lite
To answer your question:
If I want to get an array of hashes (in Ruby) of elements under "Book", what should I do next?
ruby -rplist_lite -e 'pp PlistLite.load($stdin.read)["Bookstore"]["Public"]["Books"]' <<EOS
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Bookstore</key>
<dict>
<key>Public</key>
<dict>
<key>Books</key>
<array>
<dict>
<key>Name</key>
<string>The Old Man and the Sea</string>
<key>Author</key>
<string>Hemingway</string>
</dict>
<dict>
<key>Name</key>
<string>A Brief History of Time</string>
<key>Author</key>
<string>Stephen Hawkin</string>
</dict>
</array>
</dict>
</dict>
</dict>
</plist>
EOS
output
[{"Name"=>"The Old Man and the Sea", "Author"=>"Hemingway"},
{"Name"=>"A Brief History of Time", "Author"=>"Stephen Hawkin"}]
If you don't want to require extra dependency, you can still refer to it's source code, plist_lite uses nokogiri for parsing as well:
https://github.com/tonytonyjan/plist_lite/blob/master/lib/plist_lite.rb#L37-L57
To update the plist file, use PlistLite#dump:
obj = PlistLite.load(IO.read('test.plist'))
# modify obj...
IO.write('test.plist', PlistLite.dump(obj))