class ActiveRecord::Associations::ClassMethods::JoinDependency

def construct(parent, associations, joins, row)
  case associations
    when Symbol, String
      join = joins.detect{|j| j.reflection.name.to_s == associations.to_s && j.parent_table_name == parent.class.table_name }
      raise(ConfigurationError, "No such association") if join.nil?
      joins.delete(join)
      construct_association(parent, join, row)
    when Array
      associations.each do |association|
        construct(parent, association, joins, row)
      end
    when Hash
      associations.keys.sort{|a,b|a.to_s<=>b.to_s}.each do |name|
        join = joins.detect{|j| j.reflection.name.to_s == name.to_s && j.parent_table_name == parent.class.table_name }
        raise(ConfigurationError, "No such association") if join.nil?
        association = construct_association(parent, join, row)
        joins.delete(join)
        construct(association, associations[name], joins, row) if association
      end
    else
      raise ConfigurationError, associations.inspect
  end
end