[Zope] ZODB: When to use IDs when references?

[Dieter Maurer]

Thomas Guettler writes:
 > Up to now I used relational databases. Now I don't know when it is
 > better to use IDs and when to use references.
 > 
 > Background: I write a Multiple Choice Python Product. There is a list
 > of questions and a list of users. Both get combined in the "result"
 > class. Should the class "result" have references to the questions or
 > store the question-IDs?
Ids (or paths) will give you fewer hasles...

References (understood as direct object references)
can only be handled in External Methods and Python products.
Even there, they are difficult:

  *  you can not store "wrapped" objects in the ZODB, i.e. you
     need to use "aq_base" before you store them

  *  when they are fetched, the appear at the new place in
     the site hierarchy not the original place.


Dieter