module ActiveRecord::Reflection::ClassMethods

Invoice.reflect_on_association(:line_items).macro # returns :has_many
Account.reflect_on_association(:owner) # returns the owner AssociationReflection

Returns the AssociationReflection object for the named +association+ (use the symbol). Example:

def reflect_on_association(association)
  reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
end