custom attr_reader in rails

Question

Mostly in rails if you write my_obj.attr it looks up attr in the database and reports it back. How do you create a custom def attr method that internally queries the database for attr, modifies it and returns? In other words, what's the missing piece here:

# Within a model. Basic attr_reader method, will later modify the body.
def attr
  get_from_database :attr   # <-- how do I get the value of attr from the db?
end

Answer 1

Something like that:

def attr
  value = read_attribute :attr
  value = modify(value)
  write_attribute :attr, value
  save
  value
end