Parsing large or complicated XML or JSON files is never fun, and just plain sucks. There are quite a few options for parsing XML or JSON in Ruby, such as REXML or Nokogiri for XML, and JSON in Ruby's Standard Library, none of which are very spectacular. I recently stumbled on the rubygem Crack, which is a combination of the JSON parser for Rails and the XML parser for Merb, combined and managed by GitHub user jnunemaker. This little gem will parse any XML or JSON, returning the result as a Ruby hash. This is much nicer and cleaner than the other options in my opinion (mainly XML), that return the result as an odd structure that is usually annoying to find your way through.

Take the following XML for an example:

<menu>
  <food>
    <name>Waffles</name>
    <price>5.95</price>
  </food>
  <food>
    <name>French Toast</name>
    <price>4.50</price>
  </food>
</menu>

And it's equivalent JSON:

{
  "menu": {
    "food": [
      {
        "name": "Waffles",
        "price": "5.95"
      },
      {
        "name": "French Toast",
        "price": "4.50"
      }
    ]
  }
}

These XML and JSON files can be parsed and the result returned as a Ruby hash with the following code:

require 'crack' # XML and JSON parsingrequire 'crack/json' # Only JSON parsing
require 'crack/xml' # Only XML parsing

response = Crack::XML.parse(File.read('food.xml'))
# => {"menu"=>{"food"=>[{"name"=>"Waffles", "price"=>"5.95"}, {"name"=>"French Toast", "price"=>"4.50"}]}}

response = Crack::JSON.parse(File.read('food.json'))
# => {"menu"=>{"food"=>[{"name"=>"Waffles", "price"=>"5.95"}, {"name"=>"French Toast", "price"=>"4.50"}]}}

These examples are obviously simple for the sake of this post, but this gem makes life so much simpler when parsing larger and more complicated XML or JSON.

You can install the Crack gem by issuing the following command:

gem install crack

Resources

Crack Documentation
Crack Source on GitHub
JSON Std-Lib Documentation