[Zope] OFS object attributes from a SQL DB? (ZPatterns)

[ra@burningman.com]

responding to myself here, for posterity's sake...

It turns out I _was_ on the right track... my ZClass needed to inherit 
from both DataSkin and from ZFolder.  But, for some reason, if I put 
ZFolder BEFORE DataSkin in the superclass list, then I get the error I 
mentioned below.  If, however, I put DataSkin before ZFolder, I can add 
my ZClasses exactly as I would expect.

Once I overcame this hurdle, then the pieces fell together.  I created a 
"Folder w/ Customizer Support".  Then I created a Customizer in this 
folder, and I linked it to my new object type.  I added a ZSQL Method to 
the Customizer to extract the data that I wanted from the db, and then I 
added a SkinScript in the Customizer's "Data Plug-Ins" tab to expose 
this data.

Now I can add DTML Methods in my ZClass that refer to these attributes 
and the correct data (from the SQL database) is being displayed.  Hooray!

hope-it-helps-someone-else-down-the-road'ly yours,

-r


ra@burningman.com wrote:

> Hi all,
> 
> I'm trying to create a Folder-ish ZClass that has certain attributes 
> which are actually linked to data that lives in a SQL database.  I know 
> I could just use methods to access the data, but I'm trying to gain some 
> ZPatterns foo, and it seems to me that I should be able to get this data 
> to be exposed exactly as though it were just a regular attribute on a 
> PropertySheet.  I'm having a hard time finding the magic combination, 
> though...
> 
> As I understand ZPatterns, these folder objects should be DataSkins, 
> with DataManagers that would fetch and store the data where appropriate. 
>  However, if I try to create a ZClass with both OFS:Folder and 
> ZPatterns:DataSkin as base classes, whenever I try to add it somewhere I 
> get a Key Error for "_v_dm_".
> 
> Can anyone help me discover the "right" way to use ZPatterns to make a 
> persistent Object File System type of object transparently mingle 
> attributes from PropertySheets, SQL Methods, etc.?  I know that I'm 
> close... I just can't quite wrap my head around it...
> 
> Thanks,
> 
> -r