README.markdown

• A Filter is a Ruby module with a :process method that accepts text (like MarkDown) and filters it in some way. This is for a CMS. Filters do not get stored in the database.
• A FilterGroup is (as it likely sounds) a list of Filters to apply to some piece of content. FilterGroups do get stored in the database.
• Implemented FilterArray as suggested by http://groups.google.com/group/mongomapper/browse_thread/thread/4132688f57f41d17

filter.rb

class Filter
  def initialize(name)
    @name = name
  end

  def name
    @name.gsub /\.rb/, ''
  end

  # this loads the filter module
  def filter
    @filter ||= name.camelize.constantize
  end

  def self.all
    # ...
  end

  def self.process_all(input, filter_group)
    filter_group.filters.each do |f|
      input = f.filter.process input
    end
    input
  end
end

filter_array.rb

class FilterArray < Array
  def self.to_mongo(values)
    values ||= []
    values.map { |v| v.respond_to?(:name) ? v.name : v }
  end

  def self.from_mongo(values)
    values ||= []
    values.map { |v| v.respond_to?(:name) ? v : Filter["#{v}.rb"] }
  end
end

filter_group.rb

class FilterGroup
  include MongoMapper::Document 

  key :name, String, :required => true
  key :filters, FilterArray, :required => true
end