Re: [Zope] Save references in a list as object attribut

1 Feb 2010

      Tres Seaver wrote:
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Vladislav Vorobiev wrote:
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Thierry Florac wrote:
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Le vendredi 29 janvier 2010,
  Vladislav Vorobiev <vavvav@mykniga.de> a écrit :
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Thierry thank you  for answer but it doesn't help.
I implement all what you sad. I tried with normal “list” and than 
swiched to “PersistentList”
code looks like that:
from persistent.list import PersistentList
import transaction
<snip>
myList=PersistentList([self.context.pfad, 'object])           
myList[0] = PersistentList([self.context.pfad, 'object])[0]  #hope I 
anderstud you right
ob.refList= myList 
ob._p_changed = True
ob.refList._p_changed = True 
self.context._setObject(id, ob)
After add I call again:
ob._p_changed = True
ob.refList._p_changed = True 
transaction.commit()
I see the commitet trunsactions in ZMI
The same problem. After restart ist the Attribut not in context.
For example return's
Before restart: ***1
ob.refList[0].objectValues()[0].absolute_url()
/pfad/object/FirstObjectOfReferencedObject
After restart only the id of the object:
ob.refList[0].objectValues()[0].absolute_url()
FirstObjectOfReferencedObject
Here is a place for an other question:
Normaly  self.absolute_url() returns url with hostname,  
(http://localhost/bla/bla)
but already befor restart I get without http://localhost/... see ***1
It seem's that I forgot something.  I would be glad to if somebody 
explain me this problem.
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In fact I'm not really sure to understand your data structure and it's
goals...
Could you explain me what you want to do ??
Thierry
I want to set some references from object to another object through. I try to 
explain this with example classes.
Example with two classes:
#Create classes
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class School:
  pass
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class People:
  pass
#Create objects
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p=People()
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s0=School()
s0.name="Konrad School"
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s1=School
s1.name="Leopold School"
Now I set the referece
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p.school1=s0
p.school2=s1
Now I can access through the attribut to s0 and s1 objects:
p.school1.name
“Konrad School“
This construction works persistent without problems.
The idea is to put the references in a list.
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p.schools=[s0,s1]
to access them
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p.schools[0].name
“Konrad School“
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s1.name="Leo School"
p.schools[1].name
“Leo School“
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type(p.schools[1])
<type 'classobj'>
It works in zope without restart. If the server was restartet I get some 
unwanted results. See my previews posts.
The same effects I get with PersistentLists...
I hope it is more  understandable.
You can't expect to use a simple list as an attribute of a persistent
object without taking special precautions.  Either you have methods
which mutate the list, and then set the '_p_changed' attribute to 1:
def addSchool(self, school):
      self.schools.append(school)
      self._p_changed = 1
or re-assign the list attribute:
def addSchool(self, school):
      schools = self.schools
      schools.append(school)
      self.schools = schools
You shoule be able to use a PersistentList instead of a "plain" Python
list to avoid the need for one of those two problems:
from persistent.list import PersistentList
   ...
   class Person:
       def __init__(self):
           self.schools = PersistentList()
Thank you for resonse but it doesn't help.

I post my implementation with results.

#my method
def addFotoalbom(self):
  #test with PersistentList
  self.ref_=PersistentList()
  nb=getattr(self.BoxingCategoryContainer, 'Kat 1').FOTOCAT
       self.ref_.append(nb) 
  #test without List          
self.ref=getattr(self.BoxingCategoryContainer, 'Kat 1').FOTOCAT
  return 'ok'

Results without restarting the server

1.
#absolue_url() method of of context
context.absolute_url()
'http://localhost/CategoryContainer/Kat%201/x1'

x1 is my self-object.

2.
#accessing attribute through the list
list(context.ref_[0].objectValues())[0].absolute_url()
'/testpath/CategoryContainer/Kat%201/FOTOCAT/asa'

'asa' is the first object in FOTOCAT but where is http://localhost
and why is the URL without x1/FOTOCAT?

3.
#accessing attribute without list
context.ref.objectValues()[0].absolute_url()
'http://localhost/CategoryContainer/Kat%201/x1/FOTOCAT/asa'
Thats ok.

After RESTART the Server

1.
context.absolute_url()
'http://boxapp.localhost/BoxingCategoryContainer/Kat%201/x1'

2.
list(context.ref_[0].objectValues())[0].absolute_url()
'asa'
What happaning here?

3.
#accessing attribute without list
context.ref.objectValues()[1].absolute_url()
'http://localhost/CategoryContainer/Kat%201/x1/FOTOCAT/asa'
ok

You see attributes without PersistentList survives the restart, 
PersistentList not.
Why I get some results without "http://localhost" for 
context.absolute_url() befor restart? Its 
'/testpath/CategoryContainer/Kat%201/FOTOCAT/asa' must be
'http://localhost/CategoryContainer/Kat%201/FOTOCAT/asa'.

Any Ideas?
Thanks

Vlad