There's another way to modify queries dynamically - as RDF using SPIN vocabulary: http://www.w3.org/Submission/2011/SUBM-spin-modeling-20110222/
Example QueryBuilder class: https://github.com/Graphity/graphity-ldp/blob/master/src/main/java/org/graphity/util/QueryBuilder.java Martynas graphity.org On Mon, Oct 29, 2012 at 6:31 PM, John Liu <john_ws_...@yahoo.com> wrote: > Thank you very much Andy for your quick action. > >>It will be in tonight's snapshot build of 2.7.5-SNAPSHOT (it builds at about >>05:00 UTC) > > When will Jena 2.7.5 be released? > >>Not all algebra expressions can be turned into a query. If you are >>manipulating the algebra, you can create forms OpAsQuery does not recognize. > > Can I assume that all ops which are compiled from a sparql query can be > turned back to a sparql query? For example, the following codes are always > working fine: > > AlgebraGenerator ag = new AlgebraGenerator(); > Op op = ag.compile(query); > Query query2 = OpAsQuery.asQuery(op); > > > The reason why we use these functions is that we want to add filters into the > query in runtime, for example modifying the op by adding a filter expression > (op = OpFilter.filter(e, op);), is this the best way to do that(adding a > filter)? > > Thanks, John > > > > > ________________________________ > From: Andy Seaborne <a...@apache.org> > To: users@jena.apache.org > Sent: Friday, October 26, 2012 6:19:00 PM > Subject: Re: ARQNotImplemented exception thrown by ARQ function calls > > Oversight - I've just implemented it (it's not hard!). It wil be in > tonight's snapshot build of 2.7.5-SNAPSHOT (it builds at about 05:00 UTC) > > https://repository.apache.org/content/repositories/snapshots/org/apache/jena/apache-jena/ > > By the way, you can execute algebra expressions directly: > > DatasetGraph dsg = ... > QueryIterator qIter = Algebra.exec(op, dsg) ; > > Not all algebra expressions can be turned into a query. If you are > manipulating the algebra, you can create forms OpAsQuery does not recognize. > > Andy > > On 26/10/12 22:24, John Liu wrote: >> I use some Jena arq apis to modify the query for adding filter in runtime. >> >> The query is >> >> PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> >> PREFIX onto: <http://dbpedia.org/ontology/> >> SELECT * WHERE { >> ?p a onto:Place . >> ?p geo:l* ?loc . >> } >> >> There is valid card in the line "?p geo:l* ?loc ." >> >> The funcations I used are: >> >> AlgebraGenerator ag = new AlgebraGenerator(); >> Op op = ag.compile(query); >> op = OpFilter.filter(e, op); >> Query query2 = OpAsQuery.asQuery(op); >> >> This query causes an ARQNotImplemented exception thrown in the last function >> call. The exception stack trace is: >> >> com.hp.hpl.jena.sparql.ARQNotImplemented error occurred when handling the >> REST data service. >> Not implemented: OpPath >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.visit(OpAsQuery.java:224) >> at com.hp.hpl.jena.sparql.algebra.op.OpPath.visit(OpPath.java:73) >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.asElementGroup(OpAsQuery.java:97) >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.asElement(OpAsQuery.java:88) >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.visit(OpAsQuery.java:168) >> at com.hp.hpl.jena.sparql.algebra.op.OpSequence.visit(OpSequence.java:75) >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.visit(OpAsQuery.java:473) >> at com.hp.hpl.jena.sparql.algebra.op.OpSlice.visit(OpSlice.java:50) >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.asElementGroup(OpAsQuery.java:97) >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.asElement(OpAsQuery.java:88) >> at >> com.hp.hpl.jena.sparql.algebra.OpAsQuery$Converter.visit(OpAsQuery.java:310) >> at com.hp.hpl.jena.sparql.algebra.op.OpFilter.visit(OpFilter.java:110) >> at com.hp.hpl.jena.sparql.algebra.OpAsQuery.asQuery(OpAsQuery.java:50) >> >> The arq library I used is jena-arq-2.9.1 and the jean is jena-core-2.7.1 >> >> My question is if this is bug in the arq functions? I have tested these >> functions without adding the filter(the third call), but it still throws the >> exception. >> >> If it isa bug, how can I file a defect to it? >> >> If it is not, how can I fix my code to avoid this exception. >> >> Thanks a lot for your help. >> >> John >>
