List dynamic attributes in a Mongoid Model

Question

I have gone over the documentation, and I can\'t find a specific way to go about this. I have already added some dynamic attributes to a model, and I would like to be able to it

Answer 1

I wasn't able to get any of the above solutions to work (as I didn't want to have to add slabs and slabs of code to each model, and, for some reason, the attributes method does not exist on a model instance, for me. :/), so I decided to write my own helper to do this for me. Please note that this method includes both dynamic and predefined fields.

helpers/mongoid_attribute_helper.rb:

module MongoidAttributeHelper
  def self.included(base)
    base.extend(AttributeMethods)
  end

  module AttributeMethods
    def get_all_attributes
      map = %Q{
          function() {
            for(var key in this)
            {
              emit(key, null);
            }
          }
        }

      reduce = %Q{
          function(key, value) {
            return null;
          }
        }

      hashedResults = self.map_reduce(map, reduce).out(inline: true) # Returns an array of Hashes (i.e. {"_id"=>"EmailAddress", "value"=>nil} )

      # Build an array of just the "_id"s.
      results = Array.new
      hashedResults.each do |value|
        results << value["_id"]
      end

      return results
    end
  end
end

models/user.rb:

class User
   include Mongoid::Document
   include MongoidAttributeHelper
   ...
end

Once I've added the aforementioned include (include MongoidAttributeHelper) to each model which I would like to use this method with, I can get a list of all fields using User.get_all_attributes.

Granted, this may not be the most efficient or elegant of methods, but it definitely works. :)