Restarting Zope makes Values in python class disappear
I've got a simple python class that has a data member that holds a list of strings (among other things). I can laod values into this list fine. And can query the object and the list is populated. However, after I restart Zope, the list for the class instance is empty. The other data values in my class retain their values just fine. I've got other classes that hold similar lists for which this doesn't occur. I'm banging my head against a wall - any ideas? mark@ifopen.com
----- Original Message ----- From: Mark N. Gibson <mark@ifopen.com>
I've got a simple python class that has a data member that holds a list of strings (among other things). I can laod values into this list fine. And can query the object and the list is populated. However, after I restart Zope, the list for the class instance is empty. The other data values in my class retain their values just fine.
You're probably mutating the list without informing the instance that you've changed it. If you do: thing.stufflist[4] = 'newstring' or thing.stufflist.append('newstring') ...then 'thing' has no way of knowing that 'stufflist' has changed, unless you replace 'stufflist': # This can be confusing, since it doesn't look like it does anything thing.stufflist = thing.stufflist ... or tell 'thing' explicitly: # This is the official interface to mark an object changed thing._p_changed = 1 Your changes will also get saved if you happened to change any other attributes of 'thing' in the same transaction, but as you've discovered this is unreliable at best. Explicit is better. Cheers, Evan @ digicool & 4-am
Just what I needed - Thanks! Mark
----- Original Message ----- From: Mark N. Gibson <mark@ifopen.com>
I've got a simple python class that has a data member that holds a list of strings (among other things). I can laod values into this list fine. And can query the object and the list is populated. However, after I restart Zope, the list for the class instance is empty. The other data values in my class retain their values just fine.
You're probably mutating the list without informing the instance that you've changed it. If you do:
thing.stufflist[4] = 'newstring'
or
thing.stufflist.append('newstring')
...then 'thing' has no way of knowing that 'stufflist' has changed, unless you replace 'stufflist':
# This can be confusing, since it doesn't look like it does anything thing.stufflist = thing.stufflist
... or tell 'thing' explicitly:
# This is the official interface to mark an object changed thing._p_changed = 1
Your changes will also get saved if you happened to change any other attributes of 'thing' in the same transaction, but as you've discovered this is unreliable at best. Explicit is better.
Cheers,
Evan @ digicool & 4-am
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Evan Simpson -
Mark N. Gibson