RE: [Zope] Tree tag and SQL methods?

25 Jun 1999

      [This post is old, but I haven't ended up tackling the topic until now.]
...
-----Original Message-----
From: zope-admin@zope.org [mailto:zope-admin@zope.org]On Behalf Of
Phillip J. Eby
Sent: 9. juni 1999 21:21
To: Alexander Staubo; Zope Mailing List (E-mail)
Subject: Re: [Zope] Tree tag and SQL methods?
At 07:08 PM 6/9/99 +0200, Alexander Staubo wrote:
...
I don't have a head for figuring this out today, but maybe
somebody here
can help me out.
I'm thinking of exploiting the #tree tag in conjunction with
one or more
SQL method. Say I have a hierarchical-ish table with id/parent_id
references, and I'd like to display this information in a nice
collapsible tree. Possible? Possibly the expr= or branches_expr=
arguments to #tree could evaluate the result of an SQL
method, although
it sounds to me like this would require one query per tree level.
Possibly you could put the query results of the complete table in a
temporary variable and evaluate on that?
No need.  Just include the id as a field in your result, and have your
branches_expr pass that id back into the query.  Your query
can then look
like:
SELECT * FROM data WHERE
<!--#if obj_id-->
parent_id=<!--#sqlvar obj_id-->
<!--#else-->
parent_id IS NULL
<!--#/if-->
And your tree would look like:
<!--#tree expr="query()" branches_expr="query(obj_id=obj_id)"-->
... etc.
It's been a long while since I did this, so I may be a bit off
here.  (It's
been so long in fact, that when I did it, there was no such thing as a
#sqlvar tag, and tree didn't *have* a branches_expr option!  Which made
this much more difficult to do, especially with pluggable brains thrown
into the mix.)
Nope, doesn't work. First of all, #tree doesn't seem to handle SQL
Method output the way I want -- I don't know why. Secondly, the
branches_expr expression doesn't compute because obj_id isn't a known
variable at this point; it should be written as

<!--#tree expr="query()" branches_expr="query(obj_id = _['obj_id'])"-->

But that doesn't seem to work either. Testing with a simple record with
one parent record, #tree does render one item, but I can't get at the
SQL row: For example,  inside the #tree tag gives me a
NameError exception.

So how do I do it?

--
Alexander Staubo             http://www.mop.no/~alex/
"What the hell, he thought, you're only young once, and threw
himself out of the window. That would at least keep the element of
surprise on his side."
--Douglas Adams, _The Hitchhiker's Guide to the Galaxy_