[Zope] Tree tag and SQL methods?

[Phillip J. Eby]

I looked back at what I posted, then at what I actually did in code, and
realized why what I told you is wrong.

See, here's what the tricky part of the tree tag is.  It wants as its
name/expr a single object to be the root; it doesn't grok the concept of
multiple roots.  So try it like this:

<!--#with "_.namespace(obj_id=0)"-->
<!--#tree branches_expr="query(obj_id=obj_id)"-->
...
<!--#/tree-->
<!--#/with-->

Thus, the first query looks for roots, and subsequent queries should have
obj_id filled in from the prior queries' results.  Note that query() must
look for root entries if obj_id is 0.  As you can see, there are two minor
changes from what I said before - first, there's no need to have the
expr="query()" that I told you, it only messes things up.  :)  Second, a
namespace is needed to provide a default value on the first execution of
the query.


At 02:39 AM 6/25/99 +0200, Alexander Staubo wrote:
>[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?
>>
>>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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