How to tell Ruby not to serialize an attribute or how to overload marshal_dump properly?

Question

I have an attribute in my AR:B that is not serializeable.

o = Discussion.find(6)
Marshal.dump(o)

TypeError: no marshal_dump is defined for class Proc
       from (irb):10:in `dump'

I know the culprit and what I want is to set this variable to nil before any serialization takes place.

I can do this but I'm stuck with the proper way to override marshal_dump

 def marshal_dump
   @problem = nil
   # what is the right return here?
 end

Or is there is way to tell Ruby or AR not to serialize an object?

Answer 1

Your specialized marshal_dump should return an object containing the data you want to serialize. That object will be passed back to marshal_load at load time.

In this case, I'm assuming the data you want to dump corresponds to all AR attributes (and only those), so I'd try:

def marshal_dump
  attributes
end

def marshal_load(data)
  send :attributes=, data, false  # false to override even protected attributes
end