[Zope] Basic Template question : 'truthiness'

[David H]

Mark Gibson wrote:

> I thought I knew how this stuff worked, but this has gotten me banging 
> my head against a wall.
>
> I'm trying to evaluate a condition expression, and I'm not getting 
> what I expect when using path, and I get a different result when using 
> python.  The following expressions
>
> results=<span tal:content="results" /><br />
> dosearch=<span tal:content="request/dosearch | string:NO SEARCH" /><br />
> querytpe=<span tal:content="request/querytype | string:NO QUERYTYPE" 
> /><br />
>
> <!-- test with python: this gives me what I expect -->
> <div tal:condition="python:len(results) or 
> request.get('dosearch',None) or request.get('querytype',None)">TRUE IN 
> PYTHON</div>
>
> <-- This doesn't evaluate to true -->
> <div tal:condition="results | request/dosearch | request/querytype | 
> nothing">THIS DOESN'T SHOW UP</div>
>
> ----
> Produces:
> results=[]
> dosearch=NO SEARCH
> querytpe=mps
> TRUE IN PYTHON
>
>
> As you can see, the second expression doesn't evaluate to True.  Can 
> someone explain the subtleties I seem to be missing?
>
> Thanks,
> Mark
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>
Mark,
Just looking at your second example:
<-- This doesn't evaluate to true -->
<div tal:condition="results | request/dosearch | request/querytype | 
nothing">THIS DOESN'T SHOW UP</div>

If you replace '| nothing' with '| default' you will get "THIS DOESNT 
SHOW UP"

David