On 03/05/16 11:49, Vadim Shumilin wrote:
Andy, thank you very much!
BTW, Jena documentation is not very detailed...
Contributions welcome!
As are pointers to specific areas that are unclear.
Andy
Thanks.
Vadim.
On Tue, May 3, 2016 at 12:50 PM, Andy Seaborne <[email protected]> wrote:
Hi Vadim,
A SPARQL query runs against a dataset and that what your created with the
N-Quads files.
But a dataset is not a model.
A model is just one graph.
Read the remote data into a dataset with:
Dataset ds = RDFDataMgr.loadDataset(url) ;
...
QueryExecutionFactory.create(query, ds);
...
What is happening is that at:
model.read(url);
only the default graph of the dataset at "http://localhost:3030/ds"; is
put in the model. Models are graphs (the name reflects the older 2004 RDF
terminology)
Andy
On 03/05/16 07:36, Vadim Shumilin wrote:
1) I use Fuseki2.
2) I have same test data
a) as triples in rdf file
b) as quads in nq file with graph name
from browser -- http://localhost:3030
- I uploaded the data to persistent dataset
- I see that my data successfully stored.
- I performed simple queries
#1)
SELECT ?subj ?pred ?obj WHERE { ?subj ?pred ?obj }
#2)
SELECT ?subj ?pred ?obj WHERE {
GRAPH ?g { ?subj ?pred ?obj }
}
both queries succeeded and I saw valid results.
OK, now I try to perform same queries from java program.
Here is my code:
Model model = ModelFactory.createDefaultModel();
String url = "http://localhost:3030/ds";;
model.read(url);
String RQuery = ...; //// <<< query #1 or query #2
Query query = QueryFactory.create(RQuery);
QueryExecution qe = QueryExecutionFactory.create(query, model);
ResultSet rs = qe.execSelect();
int count=0;
while (rs.hasNext())
{
QuerySolution qsol = rs.nextSolution();
++count;
}
And I have proper count for query #1 and count==0 for query #2.
Please, what is wrong with my code.
Thanks.
