On Thu, Apr 12, 2012 at 12:07 PM, David Winslow <[email protected]>wrote:
> Hi all,
>
> I'm investigating supporting rendering transformations[1] in the GeoServer
> CSS module[2]. This functionality is implemented in SLD by using OGC Filter
> encoded expressions to construct WPS processes and parameters, so I was
> expecting to be able to use ECQL to support them in CSS. However, I seem
> to be running into some trouble. Building against a recent snapshot of
> GeoTools 8, I found that the following ECQL does not work as I hoped:
>
>> gs:Contour(
>> parameter("data"),
>> parameter("levels", 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800)
>> )
>
>
> Investigating further, I see that I get a different error for undefined
> functions than for ones with a colon-delimited identifier, which suggests
> that function names don't actually support namespacing. The behavior I'm
> seeing is as follows:
>
>> scala> org.geotools.filter.text.ecql.ECQL.toExpression("f(123)")
>> org.geotools.filter.text.cql2.CQLException: Function not found. Parsing :
>> f(123).
>> scala> org.geotools.filter.text.ecql.ECQL.toExpression("g:f(123)")
>> org.geotools.filter.text.cql2.CQLException: Encountered "(" at line 1,
>> column 4.
>
>
> Should this work? Am I doing it wrong? Any insight would be appreciated.
>
>
Hum... interesting, a function starts with an indentifier, which in turn
seems to be able
to use colons inside of it:
http://docs.codehaus.org/display/GEOTOOLS/ECQL+Parser+Design
So... it seems it should work by design, but not in practice?
Not being able to use namespace qualified identifiers, e.g., foo:baz is
actually
going to pose problems filtering complex features.
Uh... wondering about that, afaik we cannot include / in the identifier
which means
xpath expressions digging into a complex feature would be prevented as
well...
> Another issue I encountered is that the SLDTransformer does not currently
> support encoding Transformations. That one I think I can resolve, but I
> want to make sure it actually works in the CSS converter before submitting
> a patch.
>
>
This one is actually solved already, just needs a review (and eventual
amendments in case there are issues):
http://jira.codehaus.org/browse/GEOT-4075
Cheers
Andrea
--
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Ing. Andrea Aime
GeoSolutions S.A.S.
Tech lead
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