well, getting one resource from the URL you can just use
Nepomuk2::Resource like so:
Nepomuk2::Resource res(url);
and you have your resource.
res.uri()
will get you the resource URI.
On 08/10/2012 05:55 PM, Dean Perry wrote:
Hi all, more noob questions:
I'm trying to write something that will retrieve the resource for
exactly one file for which I have the URL from a drag and drop
operation... I'm using the Nepomuk::Query stuff because, to be honest, I
can't make head nor tails of SPARQL yet.
So for starters:
- I know that I have a valid URL for a file
- I know its is in the database and
- using NepSAK I know that the resource has both NFO::fileName and
NIE::url associated.
I was thinking that NIE::url would be the thing to compare against:
QString urlstring = url.toString();
Nepomuk::Query::ComparisonTerm term (
Nepomuk::Vocabulary::NIE::url(),
Nepomuk::Query::LiteralTerm ( urlstring ),
Nepomuk::Query::ComparisonTerm::Equal
);
But this doesn't return any results, even when I know for certain that
the file has a resource with the NIE::url property that has the value
I'm looking for. Changing 'Equal' to 'Contains' doesn't work either.
Using NFO::fileName works fine, but returns several results if there's a
duplicate in the file system:
QString filename = urlstring.right ( ( urlstring.length() -
urlstring.lastIndexOf ( '/' ) )-1 ); // yeah, ugly...
Nepomuk::Query::ComparisonTerm term(
Nepomuk::Vocabulary::NFO::fileName(),
Nepomuk::Query::LiteralTerm(filename),
Nepomuk::Query::ComparisonTerm::Contains
);
Using the FileQuery class does not help (but adds some constraints to
the SPARQL).
I've also tried to use just the filename and 'Contains' against
NIE::url, and that doesn't work either.
As I said, I'm pretty clueless with SPARQL, but when I take the Query
generated SPARQL and paste into NepSAK the results are the same
(obvious) but when I replace the nfo::fileName with nie::url it also
doesn't work which is not very obvious to me eg:
select distinct ?r , ?v1 as ?_n_f_t_m_ex_ where { ?r nie:url ?v1 .
FILTER(bif:contains(?v1,
"'095262r00ZB_zigbee_rf4ce_sc-ZigBee_RF4CE_Specification_public.pdf'"))
. FILTER EXISTS { ?r a [ nao:userVisible "true"^^XMLSchema:boolean ] . }
. } LIMIT 20
I'm guessing I'm missing something obvious here...
cheers,
dean
Oh and secondary questions:
(1) the generated query has the stuff between ?r and ?v1 which seems
extraneous and seems to return a result with HTML markup (<b></b> tags)
that disappear if I remove them:
select distinct ?r
(bif:concat(bif:search_excerpt(bif:vector('095262r00ZB_zigbee_rf4ce_sc-ZigBee_RF4CE_Specification_public.pdf'),
?v1))) ....
vs
select distinct ?r, ?v1 ....
produces
<b>095262r00ZB</b> zigbee rf4ce sc ZigBee RF4CE Specification public.
vs
095262r00ZB_zigbee_rf4ce_sc-ZigBee_RF4CE_Specification_public.pdf
(2) is it just me or does the 'bool' parameter for
QueryServiceClient::syncQuery always return 'false' ?
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