Read a JSON document and create a new one in Rails

How can I read everything inside a JSON document and create another one with new names?

I can't find something that will help me create a new JSON file in an easy way.

Edit:

I am retrieving a ton of data in JSON format from a MongoDB database (as an array [{"xxx": "zz"}, ... ]). What I need is to cycle trough eac开发者_如何学运维h document, each field and create a new JSON document using those fields.

thanks

Here's the gist of what you want:

@keys = {
  "old" => "new",
  "foo" => "bar"
}

def rename_key(pair)
  old_key = pair.keys.first
  { @keys[old_key] => pair[old_key] }
end

pairs = ActiveSupport::JSON.decode(json)
pairs.map! { |pair| rename_key(pair) }
new_json = pairs.to_json

Obviously, you'd want to turn this into a class or two. Note that I made the assumption that all data from Mongo was in the form of simple key => value pairs, based on your description.