[Zope] Tree tag and SQL methods?

[aparna_pujar]

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----- Original Message -----
From: Alexander Staubo <alex@mop.no>
To: Zope Mailing List (E-mail) <zope@zope.org>
Sent: Thursday, June 24, 1999 5:39 PM
Subject: RE: [Zope] Tree tag and SQL methods?


> [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, <!--#var obj_id--> 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_
>
>
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