Saw ExpreUtil.parse and stopped reading. Used the second part of your
email and it worked fine. TGIF
On Fri, Dec 18, 2020 at 2:17 PM Erich Bremer <er...@ebremer.com> wrote:
> Using this will throw a "Exception in thread "main"
> org.apache.jena.query.QueryParseException: Line 1, column 2: Aggregate
> expression not legal at this point". So you may be right to use a query
> builder :-)
>
> On Fri, Dec 18, 2020 at 1:29 PM Andy Seaborne <a...@apache.org> wrote:
>
>>
>>
>> On 18/12/2020 18:04, Erich Bremer wrote:
>> > How would one create an Expr in order to add an expression like this:
>> >
>> > SPARQLParser p = SPARQLParser.createParser(Syntax.syntaxSPARQL_11);
>> > Query query = new Query();
>> > p.parse(query, "select ?year where {?s :Year ?year; :Fruit ?fruit}
>> group by
>> > ?year order by ?year");
>> > query.addResultVar("fruits","(count(?fruit))");
>> >
>> >
>> > query. addResultVar doesn't have a (String,String) but a (String,Expr)
>>
>> Expr expr = ExprUtils.parse("?x + ?y");
>>
>> But parsing count isn't so simple - it's an aggregate function.
>>
>> Aggregator agg = AggregatorFactory.createCount(true);
>> Expr exprAgg = query.allocAggregate(agg) ;
>> query.addResultVar("hello", exprAgg);
>>
>> It may be better to use the query builder.
>>
>> Andy
>>
>> >
>> > SelectHandler has a private function "parseExpr" which I pulled out a
>> copy
>> > and modified it to (Query, String) to allow passing of an external Query
>> > rather than the SelectHandler class variable query and it worked, but,
>> is
>> > there an already built in function that does the same or is there an
>> easier
>> > way to achieve the same result? - Erich
>> >
>>
>
