[Zope] Limiting depth on object creation

[Casey Duncan]

Darin Lee wrote:
> 
> Zopisitas,
> 
> I am building a threaded discussion product which integrates with a news article product I recently wrote. Inside of the article (folderish Zclass) I would like to allow my users to post "reponses." Where I am running into problems is that I would like to limit my "reply-to" depth to only three levels.
> 
> In other words, I would like to limit a user to only adding three subdirectories in a directory, or 3 folderish objects (responses) beneath a single folderish object (discussion folder). Is there an easy way to check for this? How does one accomplish this in zope?
> 
> Thanks in advance,
> -Darin Lee

You could define a method on the folderish ZClass called "depth" that
checks it's parent's depth if any and adds one to it. A python script
like so could do it (untested):

parent = context.aq_parent
if _.hasattr(parent, 'depth'):
	return parent.depth() + 1
else:
	return 1

or with DTML:

<dtml-with aq_parent only>
	<dtml-if depth>
		<dtml-return expr="depth()">
	<dtml-else>
		<dtml-return expr="1">
	</dtml-if>
</dtml-with>

Then have the constructor of your article ZClass check the depth and
raise an error if it exceeds your threshold.

-- 
| Casey Duncan
| Kaivo, Inc.
| cduncan@kaivo.com
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