[ZPatterns] Rack.getItem returning attributeless objects (ZPatterns newbie)

[Phillip Crumpler]

I tried what you suggested - still no banana :-(  So, I tried an example so
simple even I would have trouble getting it wrong.

The rack has a single SQL query, SQL_get:
  SELECT name FROM dskins WHERE dskin_id=<dtml-sqlvar dskin_id type="int">
The table has two columns, dskin_id int and name text.
The rack has a single skinscript method, with one line:
  WITH QUERY SQL_get(dskin_id=self.id) COMPUTE name
The load attribute of the rack is 'name'. The rack stores a zclass that is
derived from DataSkin, with an index_html method added, nothing else.

Still, getItem with a non existant dskin_id will return an object. Is this
suppposed to happen?

SQL_get is being called correctly and returning nil rows. Digging around a
bit in Racky.py,  the line in Rack.retrieveItem
	if hasattr(item.aq_base, a):
succeeds, even though the query returned no rows (a is the loadAttribute of
the Rack, 'name'). getattr(item.aq_base,a) returns an empty string.

Help!

Phillip

> -----Original Message-----
> From: Phillip J. Eby [mailto:pje@telecommunity.com]
> Sent: Friday, 6 July 2001 2:34 AM
> To: Phillip Crumpler; zpatterns@eby-sarna.com
> Subject: Re: [ZPatterns] Rack.getItem returning attributeless objects
> (ZPatterns newbie)
>
>
> At 12:41 AM 7/6/01 +1000, Phillip Crumpler wrote:
> >
> > I have a specialist, with the default rack, storing a zclass
> derived from
> >DataSkin. The rack is set to 'load by accessing attribute: id'.
> Within the
>
> That won't work.  The object already *has* an 'id' attribute, so the
> SkinScript that computes it will never be executed.
>
>
> >specialist are a few sql methods: SQL_get, SQL_change, SQL_create,
> >SQL_delete. The table has two columns, id (int) and name (text).
> The zclass
> >has a simple index_html method to show the instance's id and name
> >attributes.
> >
> >The rack has a skinscript method like so:
> >
> >WITH SQL_get(id=self.id) COMPUTE id, name
>
> Try making this:
>
> WITH QUERY SQL_get(id=self.id) COMPUTE name
>
> And making the 'name' attribute be the "load" attribute.
>
>
>
>
> >WHEN OBJECT ADDED CALL SQL_create(id=self.id, name=self.name)
> >
> >WHEN OBJECT CHANGED STORE id, name USING SQL_change(id=self.id,
> >name=self.name)
> >
> >WHEN OBJECT DELETED CALL SQL_delete(id=self.id)
>
> The rest of this looks fine.
>
>
> >I'm new to skinscript, so I'm not too sure about this. The only
> other Data
> >Plug-In in the rack is a SpecialistPlugIn (but the Specialist
> itself has no
> >Data Plug-Ins)
> >
> >My (first) problem is this: a call to Rack.getItem will _always_
> return an
> >instance - if SQL_get returns no rows then it just ends up with no
> >attributes.
>
> Right, because the object already has an id.
>
>
> > I could always just get brutal and insert it into the database
> directly but
> >I think that would really be missing the point ;^)  How do I make
> >Rack.getItem return None in this case?
>
> Change to using a load attribute that's actually dependent on the
> result of
> the query.
>