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From Ross Gardler <>
Subject Re: Locationmap now works for repositories
Date Tue, 07 Jun 2005 16:25:57 GMT
Tim Williams wrote:
> On 6/7/05, Ross Gardler <> wrote:
>>Tim Williams wrote:
>>>On 6/6/05, Ross Gardler <> wrote:
>>>>Tim Williams wrote:
>>>>>On 6/6/05, Ross Gardler <> wrote:
>>>>>>Tim Williams wrote:
>>>>><map:select type="exists">
>>>>>    <map:when test="{project:content.xdocs}tabs.xml">
>>>>>         <map:generate src="{project:content.xdocs}tabs.xml"/>
>>>>>    </map:when>
>>>>>    <map:when test="{lm:tabs.xml}">
>>>>>         <map:generate src="{lm:tabs.xml}"/>
>>>>>     </map:when>
>>>>This is interesting. Have you tested what happens when {lm:tabs.xml}
>>>>does not point to anything useful? That is, does the second <map:when>
>>>:( Sadly, no.  It looks like {lm:tabs.xml} always evaluates to
>>>existing.  Are locationmaps not usable in an exists selector for some
>>My guess is (there's another disclaimer, I haven't tested this yet)...
>>Since you are mapping the {lm:tabs.xml} to a http request a document is
>>always returned. It may be a 404 error, but it is still a document. To
>>confirm this we would need to look at the generator code and, if
>>necessary detect error conditions from the various repository types.
> The problem or at least a symptom appears to be with the resolver
> inside the select method of SourceExistsSelector.  Here's my
> rationale:
> o) LocationMapModule appears to properly be responding with null if a
> particular hint is not found.

This is different from what I intended to ask above. I meant if the hint 
*does* resolve to something sensible in the locationmap (e.g. what happens.

What you appear to have tested is what happens if the locationmap does 
not have a match for the resource.

> o) The empty string comes into SourceExistsSelector and for some weird
> reason the resolver resolves it to
> "file:/C:/src/apache-forrest-7-branch/main/webapp/" (for me, but you
> get the idea).

This is not weird if one knows the internals of Cocoon. This location is 
  the context root for your installation of Cocoon. This is were 
everything is relative to. So, since we have a null from the locaitonmap 
module we are looking in the root.

> o) Obviously calling src.exists() on the above location returns true
> causing the map:when to always evaluate to true even when no hint is
> found in the locationmap.

This is an interesting point...

> I've got a temporary hack in place by testing for an empty uri
> parameter immediately before it even gets to the resolver.  This gets
> me the behaviour I would expect in an exists selector test 

Does it get the behaviour you expect. Have you tried having a valid 
match in the locationmap but not having the resource present at 
indicated location?

> but I'm
> thinking it'd be best if someone who knows exactly how the
> resolver/SourceExistsSelector works took a look at it.  In the mean
> time, I could use my little hack to keep moving.

I would have thought we can just check for a null in the 
SourceExistsSelector. However, this is a Cocoon component not a Forrest 
one so we need to take this to Cocoon. I don't have the time to follow 
it through just yet, maybe next week.

Could you provide a patch to the locationmap branch for the stuff that 
you have done so that we can both see the same code.

> Make sense?

It certainly does, thanks.


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