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From Tim Williams <william...@gmail.com>
Subject Re: Locationmap now works for repositories
Date Tue, 07 Jun 2005 16:12:40 GMT
On 6/7/05, Ross Gardler <rgardler@apache.org> wrote:
> Tim Williams wrote:
> > On 6/6/05, Ross Gardler <rgardler@apache.org> wrote:
> >
> >>Tim Williams wrote:
> >>
> >>>On 6/6/05, Ross Gardler <rgardler@apache.org> 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>
> >>></map:select>
> >>
> >>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>
work?
> >
> >
> > :( Sadly, no.  It looks like {lm:tabs.xml} always evaluates to
> > existing.  Are locationmaps not usable in an exists selector for some
> > reason?
> >
> 
> 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.

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).

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.

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 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.

Make sense?
--tim

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