[Zope] Exporting zodb data (Urgent)

[Paul Winkler]

On Sun, Jun 29, 2003 at 02:20:45AM +0530, Sukhwinder Singh wrote:
> Hello,
> 
> Thanks for replying.
> 
> It is a school application which stored information about employees,
> students, trainings etc.
> What I know is they have used dtml methods, python scripts and folders to
> organize their app. But not custom products. I have checked those objects
> using /manage. And most of these are methods and other dtml files. I have
> also checked some of the dtml files.and python scripts.

I'm still wondering why this app is slow.  I would hazard a guess that
the implementation is not adequate to the number of objects. 
E.g. there might be something like

for foo in some_folder.objectItems():
    do something with a property of foo
   
... which is fine when some_folder contains a small number of objects,
but when it grows to thousands, this will be very inefficient.
Even worse would be using zope_find() which is really meant to
be a convenience for developers and administrators, not for
application code.

Such an application should be redesigned to use ZCatalog which is
very fast.

Of course this is only a guess, and optimization should NEVER be based
on guesses, that is what profiling is for.

I still don't understand how you are expected to do this job.
To make an analogy, if I needed to extract a large data set from
a MySQL database, I wouldn't give the task to someone who had
never used SQL before. If I wanted to re-implement a Smalltalk 
application in Java, I wouldn't hire a java developer who has never 
used smalltalk.  No wonder you're finding this difficult.

But I guess it's too late, the boss has dictated PHP and you
are stuck with the task. So I'll try to give you what you
want, no matter how wrong I think it is :)

> These files get data using something like:
> 
> for employee in container.employees
> print employee.name

well, i'm still only guessing what the real code is, since that
doesn't look like anything that really works.

Since you say there's nothing but folders, python scripts and DTML,
I guess that maybe there is a DTML Document that represents each
employee, and I further guess that they are using Properties to store
data about each employee. Mind you, this is only a guess.
You could verify this by looking at the Properties tab on some of 
the objects that represent employees.

> These files/scripts/methods are in their respective folders. For example, a
> script which displays employee data is in employees folder and script which
> exports student data is in students folder.
> 
> But when I try to use this method of using for each * in container.students
> or container.employees outside these folders (in the root folder) error is
> displayed like container is not defined etc. Is container something built in
> or their custom class?

"container" is a bound name that's always available in Python Script (and
in Page Templates which you don't seem to be using).  It refers to the
container (usually a Folder) in which the Script object lives.
This is described in the Advanced Scripting chapter of the online 
Zope Book.

The "container" name is NOT bound in an External Method, nor is it
bound in DTML.
In an External Method, you can use "self" instead (if self is the first
parameter of the function definition bound to the external method).
In DTML, it's typical to just ask for the name without a qualifying
namespace like "container". DTML then automagically looks in many
places for this name.

> If there is no other solution than learning zope then tell me what are the
> things I should learn about only to export data. I have downloaded zope
> guide 

Do you mean the Zope Book?

> and developer guide

Probably not much help to you, it's for developing add-on Products.

> and admin guide.

Dead project as far as I know, and probably not relevant anyway.

You might find this chapter of the online Zope Book very useful:
http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/ScriptingZope.stx
I suspect the section on "The Zope API" will be particularly
useful, once you understand the differences between Scripts
and External Methods etc.

That chapter builds on concepts that are described in earlier chapters:

http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/UsingZope.stx
(introduces Properties, among other things)

http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/Acquisition.stx
(introduces Acquisition, very important)

http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/DTML.stx
(basic DTML)

http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/AppendixE.stx
(describes how names are looked up in dtml-var expressions)

-- 

Paul Winkler
http://www.slinkp.com
Look! Up in the sky! It's FJUK- XENON MEGA!
(random hero from isometric.spaceninja.com)