[Zope-dev] ZPatterns: persistant objects hold DataSkin-Items -> KeyError: _v_dm_

[Phillip J. Eby]

At 02:49 PM 12/14/00 +0100, Ulrich Eck wrote:
>
>after a while I think I got it now.
>
>I use a FcWS as a Folder like usual in Zope and if i create an object
>of a type which is "customized" certain attributes will be set through
>the customizer. 

Yes.


>so for a database app that handles multiple tables
>it isnt useful to handle with a FwCS.

Um, not necessarily.  You can create regular Folders under the FwCS if you
want to keep them seperate.  You can even use BTreeFolders or other
ObjectManagers, if you like.  All that's required is that they support the
ObjectManager protocol.  So you can have a folder for each meta_type.  Of
course, the primary storage of the object has to be the ZODB.


>First I thought there is the same "magic" as if i ..getItem() with a
>specialist .. in a FwCS

No.  The FwCS is to allow more "traditional" Zope objects to blend in data
from other sources, and/or to have trigger support.


>Due to the Folders Rules, there can only by one object with the same id
>at a time in one FwCS ..

Yes.   But you don't have to place the DataSkins directly under the FwCS,
they can be any number of nesting levels below it.


>I'll switch back to a Specialist which has many racks as data-providers
>which i can choose the right one with a method that has a "meta-type"
>parameter.
>
>is this right so far ??

Pretty much, although I'm not sure why you want to pick by meta type, since
one of the major reasons for having a Specialist is for the rest of the
application not to know about specific meta types.