On 10/05/11 17:28, Andrea Aime wrote:
On Tue, May 10, 2011 at 6:31 AM, Niels<niels.charl...@csiro.au> wrote:
What I mean is for example filtering on the following equation:
a/b/c = "foo"
Hum... OGC filter against features is xpath based.
Soo... when I say a = 10 against a simple feature the corresponding xpath
filter would be:
feature[a = 10]
whilst doing what you say against a complex one would result in:
feature[a/b/c = 10]
where, as you say, some between a, b or c is multivalued (so we're actually
looking at a list if not a tree).
Is this even valid? What would it mean? Afaik you can do something like:
feature[a/b/c[1] = 10]
that is, select the specific subelement to test (assuming c is the
multivalued bit).
But what would be the meaning of the former writing? all a/b/c
subelements must be equal to 10?
Just one? Afaik the xpath engine would return a list of elements and
the comparison would fail.
Yes, it is very valid. The X-Path standard explicitely says that the
filter [a/b/c = 10] with a/b/c returning multiple values will return
true if the equation returns true for any of these values. This is
exactly the approach I have been following here, too. So if the OGC
filter is X-path based as you call it, I am absolutely right to make the
filter systems in Geotools support this by default!
--
*Niels Charlier*
Software Engineer
CSIRO Earth Science and Resource Engineering
Phone: +61 8 6436 8914
Australian Resources Research Centre
26 Dick Perry Avenue, Kensington WA 6151
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