I've moved your question to zope-dev, as that's where ZPatterns questions probably belong. Roche wrote:
I created a ZClass called "Product" with Dataskin as baseclass.
I also added a specialist called ProductManager containing a default rack. Under storage for the rack I selected the newly created Product ZClass.
My product ZClass needs to query both a RDBMS and the ZODB for attributevalues. At this point I get lost. I guess i should add an attributeprovider plug-in???
The easiest way is to use a couple of SheetProviders. Use a PersistentSheetProvider for your ZODB values. You'll have to write your own one for SQL values. You will need to create the appropriate propertysheets in your ZClass class definition in your product.
What should go into the fromexpr and attrsexprs properties of the attributeprovider? Should one add an attributeprovider for each attribute of the product?
See the IRC chat log: http://www.zope.org/Documentation/Chats/zpatt_chat_log An attribute provider can provide multiple attributes. You can have multiple attribute providers if you like. -- Steve Alexander Software Engineer Cat-Box limited http://www.cat-box.net