[Zope-dev] Q/ regarding 'Broken Product'

[Jim Fulton]

Thomas Riedl wrote:
> 
> Ah, I like turn around THAT short.
> You guys at DigiCool are simply great!

I try to pay close attention to anything
having to do with the database. :)

> ....
> >> =======================
> >> Whenever there's a "severe" error (like a syntax error in the Product
> >> python code), I see a 'broken Product'.
> >>
> >> Sometimes I'm able to fix the error and to then reuse my created Product
> >> instances and all its subsidiary objects.
> >>
> >> Sometimes the Product instance will have ceased to exist, which is quite a
> >> P.I.T.A.
> >
> >I've never seen this.  It would be interesting to use the bbb.py script in
> >the utilities directory (of Zope 2.0a1 or in the public CVS) to create an XML
> >rendition of your database.  This might give you a better idea where your data
> 
>has gone. :)
> 
> I tried, but it breaks on importing 'ppml' when I try to report xml. See
> below...

Is there a ppml.py in your utilities directory?  If not, I can send it to you, 
however, I see what your problem is wrt disappearing instances.  See below.
 
> >Uh, what exactly do you mean by ceased to exist?  What is your evidence
> >for this?  Do they no longer show up in otherwise functioning folders?
> 
> My evidence looks like this:
> I have my Product, XXX.
> I instatiate it.
> It works.
> I break it (by e.g. syntax errors).
> I fix them.
> I change into the /Control Panel/Products
> folder; there's then my still broken Product.
> clicking on it sometimes reveals an instance (created earlier via selecting
> 'XXX' from the selection list, clicking 'Add', a.s.o.), and sometimes
> that (or those) instance(s) aren't visible any longer.
> The XXX Folder reads
>         'There are currently no items in Broken product XXX'
> and offers the 'add something' selection list.
> 
> I believe to have found out this pattern:
> Especially tricky seem to be changes with / deletions of method names, but
> sometimes a carefully left out (;-) paren will do, as long as the error
> occurs in Zope's startup phase.

Ah.  The fact that Zope lets you add items to a Python product
(as apposed to a through-the-web product) is a bug. I'll add this to
the bugs list.

When a Python-based product changes state from broken to OK or
OK to broken, the Zope product object gets recreated.  

Add your instances to a folder in the main tree or in a
through-the-web product.

 
> >> Nevertheless, the Product keeps on showing up as 'Broken', including its
> >> out-dated Traceback, until I "delete" it and restart Zope.
>  >
> >What version of Zope are you using?  I thought 1.10.2 got this right.
> 
> It is 1.10.2, running on a Linux RedHat-5.2 box, python-1.5.1, using
> Zope's own HTTP server (like "python serve.py").

Hm.  Waaaa. I know this is fixed in the current code.

 
> >> Q#1: How can I 'mend' a broken Product w/o deleting it?
> >
> >You *should* be able to just mend it.  If it doesn't show up
> >as mended, then there is a Zope bug.
> 
> Well, then I regard this an undocumented feature... I think it
> doesn't stem from my browser caching data, since I changed its amount
> of cache down to 2k (you know, Netscape and its 'caching' of erroneous
> pages by the last error-free content ...).

I'm guessing that it is a bug in 1.10.2.  This is fixed in 2.0.
In the mean time, you will have to work around the problem by
moving (deleting) the product.  Note that another work-around
may be to modify (create) a version.txt in the product folder.
Also note that, even through the product shows up as broken, 
you may still have a functioning product. Do your product items
show up in the add list?
 
> >> Q#3: When I change attributes of e.g. an anonymous keyword object: will
> >>         this inevitably result in the often_heard_of database
> >>         inflation 'til next pack day?
> >
> >I'm not sure what you are refering to here.  When you change any
> >(persistent) object, a new version of the object is written to the database.
> >The old version is retained until it is packed.
> 
> That's what I intended to ask for.
> 
> So, what shall I do upon the next mysterious disappearance on instances?

See above.  Don't poke instances into the product folder (of a Python
written product.)

Jim

--
Jim Fulton           mailto:jim@digicool.com
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