[Zope] DTML Container?

[James W. Howe]

At 07:40 PM 2/8/00 +0700, Mike wrote:
>Steve Spicklemire wrote:
> >
> > Hi Mike,
> >
> >    Hmmm.. how about just letting each instance of your
> > ObjectManagerish ZClass contain a "DTML Method" called
> > story_dtml or something. Then the index_html method of
> > the Zclass could (among other things possibly..) call
> >
> > <dtml-var story_dtml>
>
>I have two objections:
>
>1) aggregation is NOT inheritance.
>2) when you try index such object in ZCatalog (I mean full text index)
>you get story_dtml indexed, not object itself. How will you handle such
>catalog entries?

I've been working on something very similar for the past few weeks.  I 
needed an object to hold onto a news article including attributes such as 
headline, publishing date, photo, etc.  I created a ZClass called Article 
which derives from ZCatalogAware and ObjectManager (plus a couple 
others).  I use a technique similar to the one described by Steve.  I store 
my simple properties as properties, but I store the article in a DTMLMethod 
contained by my object under the name of "article_content".  If there is a 
photo associated with the story, I store a CaptionedImage (another object I 
created) under the id of "photo".  My article itself has no knowledge of 
how it might be displayed.  The author of the article can include some HTML 
tags within the article itself for things like bold, italic, but more 
complex formatting is discouraged.  I have developed several "view" objects 
(actually folders which contain DTMLMethods), which can display 
articles.  So far this has worked quite well for me.

As to your objections:

1. I'm not concerned about aggregation vs. inheritance.  My Article 
inherits folder behavior which lets it maintain a collection of specific 
items relating to the article.  I think of the collection as my objects 
instance variables.

2. I was concerned about this as well.  However I have a solution which 
seems to work (there may be other solutions as well).  All I did was create 
a ZCatalog and specified "article_content" as a TextIndex for the 
catalog.  I did a Find for all objects with a meta-type of 'Article'.  I 
was able to catalog all my articles and I can do full text searches as well 
even though the article content is in a DTMLMethod.  There have been some 
other suggestions on this list to use the PrincipiaSearchSource mechanism.

Hope you find this useful.  Feel free to ask questions.

James W. Howe				mailto:jwh@allencreek.com
Allen Creek Software, Inc.		pgpkey: http://ic.net/~jwh/pgpkey.html		
Ann Arbor, MI  48103