Import this to get searchlogic-style scopes from metasearch and rails 3

meta_search_hacks.rb

# by Paul Callaghan, Nov 2010. 

# this uses method-missing to trigger generation and execution of the corresponding relation 
# eg Product.name_equals("yay") 

# TODO: M_S doesn't check for unexpected values, eg match failures in
#       matches_attribute_method (so we trap exceptions)

module MetaSearchHacks
  def self.build_rel(base_or_scope, method, *args)
    begin
      MetaSearch::Builder.
        new(base_or_scope).
        method_missing(method.to_s + '=', *args) 
    rescue => e
      return nil
    end
  end
end

# fix for relation/scope values
class ActiveRecord::Relation
  include MetaSearchHacks

  def method_missing_with_metasearch(method, *args) 
    if relation = MetaSearchHacks.build_rel(self.klass, method, *args)
      return self.merge(relation)

    elsif self.respond_to? :method_missing_without_metasearch
      self.method_missing_without_metasearch(method, *args)

    else
      raise "Couldn't run instance's original method_missing()"
    end
  end
  alias_method_chain :method_missing, :metasearch
end

# but for models, we want to create new scope-like things
class ActiveRecord::Base
  # this alias must be done in the singleton class
  class << self
    # alias_method_chain :method_missing, :metasearch
  end
end

class ActiveRecord::Base
  include MetaSearchHacks

  protected
  def self.method_missing_with_metasearch(method, *args) 
    if relation = MetaSearchHacks.build_rel(self, method, *args)
      return relation
    else
      # respond_to doesn't like private/protected methods?
      self.send(:method_missing_without_metasearch, method, *args)
    end
  end

  # this alias must be done in the singleton class
  class << self
    alias_method_chain :method_missing, :metasearch
  end
end