Ah yes, I vaguely remember reading that now that you mention it, and as
that's exactly what I'm trying to do, I'm sure that's what is happening.
Sorry, too much to keep track of.
Any rough idea if/when that will be added? Our implementation REALLY
needs a way to create and use re-usable SPARQL Filter SPIN functions,
and from what I can tell right now, the only way to implement them is to
use sub-selects, unless of course the Jena folks were to implement the
previously suggested "MATCH" assignement capability (I won't hold my
breath on that one) :-)
As an interesting side note, using a subselect with a reference to a
SPIN function from the TBC SPARQL tab DOES work. e.g. with
getProjectUser defined as a SPIN Function this works:
SELECT ?value
{
{SELECT ?user
WHERE {
LET(?user := :getProjectUser("DEFAULT_PROJECT", "jeff"))
}
}
{SELECT ?user ?value
WHERE {
?user :firstName ?value
}
}
}
Thanks!
Jeff
p.s. as a very ironic side note, my ctrl key has stopped working. Guess
it didn't like me disparaging ctrl-space.
> -----Original Message-----
> From: Holger Knublauch [mailto:[email protected]]
> Sent: Thursday, May 28, 2009 2:32 PM
> To: [email protected]
> Subject: [tbc-users] Re: [SPIN] Using FILTER with function arguments
>
>
> Hi Jeff,
>
> as posted a few weeks ago, SPIN RDF syntax does not support
> sub- selects yet. Maybe this is what you are experiencing here?
>
> Holger
>
>
> On May 28, 2009, at 11:14 AM, Schmitz, Jeffrey A wrote:
>
> >
> > For some reason, I'm having trouble executing the
> "sub-query" sparql
> > query using the SPIN api. Even after simplifying the query
> to remove
> > the LET and the SPIN function, the query with sub-queries doesn't
> > return results when it should.
> >
> > Specifically, when I execute the following query in my code
> using the
> > SPIN API, as well as when I execute it from the TBC SPARQL tab, it
> > works
> > correctly:
> >
> > SELECT ?value
> > WHERE {?user a ModelManagement:User .
> > ?user ModelManagement:firstName ?value
> > }
> >
> > However, when I execute the following, I think logically equivalent
> > query, I get no results:
> >
> > SELECT ?value
> > {
> > {SELECT ?user
> > WHERE {
> > ?user a ModelManagement:User .
> > }
> > }
> > {SELECT ?user ?value
> > WHERE {
> > ?user ModelManagement:firstName ?value
> > }
> > }
> > }
> >
> > This query does work correctly from the TBC SPARQL tab, and
> I can also
> > run this query in my code using just the jena/arq API and it works
> > correctly.
> >
> > I've pasted below the code I use to execute the queries
> using the SPIN
> > API, which seems to work for most cases. I have a feeling
> there's a
> > more concise way to do this, but that's a topic for another post...
> >
> > //Create the ARQ Query from the SPARQL string.
> > arqQuery = QueryFactory.create(sparqlStr,
> Syntax.syntaxARQ);
> >
> > //Get the ARQ2SPIN utility, specifying model to
> be queried.
> > ARQ2SPIN a2s = new
> > ARQ2SPIN(modelManagementInst.memModel);
> >
> > //Create a SPIN query from the ARQ Query
> > org.topbraid.spin.model.Query spinQuery =
> a2s.createQuery(arqQuery,
> > null);
> >
> > //Wrap up both queries in a SPIN wrapper.
> > QueryWrapper wrapper = null;
> > String ruleText = null;
> > if (spinQuery != null) {
> > StringPrintContext p = new StringPrintContext();
> > spinQuery.print(p);
> > if (ruleText == null) {
> > ruleText = p.getString();
> > }
> > arqQuery =
> > ARQFactory.get().createQuery(modelManagementInst.memModel,
> >
> > p.getStringBuilder().toString());
> > wrapper = new QueryWrapper(arqQuery,
> ruleText, spinQuery,
> > ruleText);
> > }
> >
> > //Get the arq query from the wrapper
> > arqQuery = wrapper.getQuery();
> >
> > //Get the query execution
> > QueryExecution selQe =
> > ARQFactory.get().createQueryExecution(
> > arqQuery,
> > modelManagementInst.memModel);
> >
> > //Execute it
> > ResultSet rs = selQe.execSelect();
> >
> >
> >> -----Original Message-----
> >> From: Schmitz, Jeffrey A
> >> Sent: Thursday, May 28, 2009 11:06 AM
> >> To: [email protected]
> >> Subject: [tbc-users] Re: [SPIN] Using FILTER with function
> arguments
> >>
> >>
> >> No, that's not working in this case...
> >>
> >> SELECT ?user ?value
> >> WHERE {
> >> LET(?user := :getProjectUser("DEFAULT_PROJECT", "xxx")) FILTER
> >> (bound(?user)) ?user :firstName ?value }
> >>
> >> Still returns everything with a firstName property.
> >>
> >>> -----Original Message-----
> >>> From: Holger Knublauch [mailto:[email protected]]
> >>> Sent: Thursday, May 28, 2009 10:22 AM
> >>> To: [email protected]
> >>> Subject: [tbc-users] Re: [SPIN] Using FILTER with
> function arguments
> >>>
> >>>
> >>> Jeff,
> >>>
> >>> wouldn't it be sufficient to add a FILTER bound(?var) after the
> >>> function call?
> >>>
> >>> Holger
> >>>
> >>>
> >>> On May 28, 2009, at 7:06 AM, Schmitz, Jeffrey A wrote:
> >>>
> >>>>
> >>>> "The function returns no binding and therefore ?user is
> >> unbound and
> >>>> will be iterating over all possible subjects of the firstName
> >>>> triples."
> >>>>
> >>>> Hmmm, not what I was expecting. I guess I would have
> >>> expected it to
> >>>> act more like normal SPARQL variable chaining occurrs,
> >> e.g. in the
> >>>> following
> >>>> query:
> >>>>
> >>>> SELECT ?user ?value
> >>>> WHERE {?user a :NonExistantClass .
> >>>> ?user :firstName ?value}
> >>>>
> >>>> ?user is "unbound" after the first line
> (NonExistantClass doesn't
> >>>> really exist), and this query returns no results instead of
> >>> everything
> >>>> in the model with a firstName property. Even if you reverse the
> >>>> order:
> >>>>
> >>>> SELECT ?user ?value
> >>>> WHERE {?user :firstName ?value .
> >>>> ?user a :NonExistantClass .
> >>>> }
> >>>>
> >>>> You still get no results. But change it to something like:
> >>>>
> >>>> SELECT ?user ?value
> >>>> WHERE {(LET ?user := :filterOnClass(:NonExistantClass)
> >>>> ?user :firstName ?value}
> >>>>
> >>>> And you do get everything in the model with a firstName property.
> >>>>
> >>>> Be that as it may, using subqueries I think I'm able to get the
> >>>> behavior I'm looking for. A little verbose, but if I understand
> >>>> things, I think you'd have to do this anytime you wanted
> to use a
> >>>> re-usable SPIN filtering function:
> >>>>
> >>>>
> >>>> SELECT ?user ?value
> >>>> {
> >>>> {SELECT ?user
> >>>> WHERE {
> >>>> LET(?user :=
> >>>> ModelManagement:getProjectUser("DEFAULT_PROJECT",
> >>>> "xxx"))
> >>>> }
> >>>> }
> >>>> {SELECT ?user ?value
> >>>> WHERE {
> >>>> ?user ModelManagement:firstName ?value
> >>>> }
> >>>> }
> >>>> }
> >>>>
> >>>> In the above query, if the user specified in the LET
> >> (xxx) doesn't
> >>>> exist, nothing is returned.
> >>>>
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: Holger Knublauch [mailto:[email protected]]
> >>>>> Sent: Wednesday, May 27, 2009 9:38 PM
> >>>>> To: [email protected]
> >>>>> Subject: [tbc-users] Re: [SPIN] Using FILTER with function
> >>> arguments
> >>>>>
> >>>>>
> >>>>>
> >>>>> On May 27, 2009, at 12:21 PM, Schmitz, Jeffrey A wrote:
> >>>>>
> >>>>>>
> >>>>>> It's getting curiousor and curiousor...
> >>>>>>
> >>>>>> Using the TBC SPARQL tab, when I call a function that filters
> >>>>>> according to an argument, e.g.:
> >>>>>>
> >>>>>> SELECT ?user
> >>>>>> WHERE {
> >>>>>> ?project ModelManagement:hasUser ?user .
> >>>>>> ?user Common:name ?username .
> >>>>>> FILTER (?username = ?arg1) .
> >>>>>> }
> >>>>>
> >>>>> If the function returns no binding then it will be
> >> comparable to a
> >>>>> wildcard in the query below.
> >>>>>
> >>>>>>
> >>>>>>
> >>>>>> As long as I pass in an argument that has a match:
> >>>>>>
> >>>>>> SELECT ?value
> >>>>>> WHERE {LET(?user := ModelManagement:getProjectUser("john"))
> >>>>>> ?user ModelManagement:firstName ?value}
> >>>>>>
> >>>>>> the function returns just one result as expected (in this
> >>> case for
> >>>>>> some reason the blank result rows aren't returned).
> >>> However, if I
> >>>>>> pass in a value that has NO matches:
> >>>>>>
> >>>>>> SELECT ?value
> >>>>>> WHERE {LET(?user := ModelManagement:getProjectUser("xxx"))
> >>>>>> ?user ModelManagement:firstName ?value}
> >>>>>>
> >>>>>>
> >>>>>> It acts like the FILTER statement isn't there, and all
> >>>>> User's names in
> >>>>>> the model are returned. I would have expected no
> results to be
> >>>>>> returned. Btw, I'm seeing this same behavior in my code
> >>> too. Am I
> >>>>>> thinking about this wrong, or is there perhaps a
> >> problem with how
> >>>>>> FILTER works within a Function?
> >>>>>
> >>>>> No, the behavior is correct (as far as I understand your
> >> example).
> >>>>> The function returns no binding and therefore ?user is
> >> unbound and
> >>>>> will be iterating over all possible subjects of the firstName
> >>>>> triples.
> >>>>>
> >>>>> In your first email, please keep in mind that the
> >>> execution order of
> >>>>> ARQ might be different from what you have typed it. In
> >>> particular, I
> >>>>> find often that LET statements are executed at the end,
> >>> and therefore
> >>>>> lead to more iterations than expected.
> >>>>>
> >>>>> Holger
> >>>>>
> >>>>>
> >>>>>>
> >>>>>
> >>>>
> >>>>>
> >>>
> >>>
> >>>>
> >>>
> >>
> >>>
> >>
> >
> > >
>
>
> >
>
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