HAVING clause with variable comparison not correctly evaluated

[white-gecko]

On the graph

<urn:a> <urn:p> 1 .
<urn:b> <urn:p> 3 .
<urn:c> <urn:q> 1 .

I would expect the query

SELECT ?p ?o
WHERE { ?s ?p ?o }
GROUP BY ?p HAVING (?p != <urn:foo> )

to result in

?p	?o
urn:p	one of 1 or 3
urn:q	1

while it results in an empty result set.

This issue is demonstrated in pull request #935 .

rdflib/test/test_having.py

Lines 8 to 12 in 7610e18

	data = """
	<urn:a> <urn:p> 1 .
	<urn:b> <urn:p> 3 .
	<urn:c> <urn:q> 1 .
	"""

rdflib/test/test_having.py

Lines 33 to 39 in 7610e18

	def testHavingPrimaryExpressionVarNeqIri(self):
	query = ("SELECT ?p ?o "
	"WHERE { ?s ?p ?o } "
	"GROUP BY ?p HAVING (?p != <urn:foo> )")
	qres = self.g.query(query)
	self.assertEqual(2, len(qres))

[white-gecko]

I think the problem is in the parser. When I look at the algebra, the RelationExpression: RelationalExpression_{'expr': rdflib.term.Variable('p'), 'op': '!=', 'other': rdflib.term.URIRef('urn:foo'), '_vars': set()} is comparing with rdflib.term.Variable('p') while it has to be rdflib.term.Variable('__agg_1__') because of the GROUP BY ?p as can be seen in the AggregateJoin_.

SelectQuery_SelectQuery_{'p': Project_{'p': Extend_{'p': Extend_{'p': Filter_{'expr': RelationalExpression_{'expr': rdflib.term.Variable('p'), 'op': '!=', 'other': rdflib.term.URIRef('urn:foo'), '_vars': set()}, 'p': AggregateJoin_{'A': [Aggregate_Sample_{'vars': rdflib.term.Variable('p'), 'res': rdflib.term.Variable('__agg_1__'), '_vars': {rdflib.term.Variable('p'), rdflib.term.Variable('__agg_1__')}}, Aggregate_Sample_{'vars': rdflib.term.Variable('o'), 'res': rdflib.term.Variable('__agg_2__'), '_vars': {rdflib.term.Variable('o'), rdflib.term.Variable('__agg_2__')}}], 'p': Group_{'p': BGP_{'triples': [(rdflib.term.Variable('s'), rdflib.term.Variable('p'), rdflib.term.Variable('o'))], '_vars': {rdflib.term.Variable('p'), rdflib.term.Variable('o'), rdflib.term.Variable('s')}}, 'expr': [rdflib.term.Variable('p')], '_vars': {rdflib.term.Variable('p'), rdflib.term.Variable('o'), rdflib.term.Variable('s')}}, '_vars': {rdflib.term.Variable('o'), rdflib.term.Variable('__agg_1__'), rdflib.term.Variable('__agg_2__'), rdflib.term.Variable('s'), rdflib.term.Variable('p')}}, '_vars': {rdflib.term.Variable('o'), rdflib.term.Variable('__agg_1__'), rdflib.term.Variable('__agg_2__'), rdflib.term.Variable('s'), rdflib.term.Variable('p')}}, 'expr': rdflib.term.Variable('__agg_1__'), 'var': rdflib.term.Variable('p'), '_vars': {rdflib.term.Variable('o'), rdflib.term.Variable('__agg_1__'), rdflib.term.Variable('__agg_2__'), rdflib.term.Variable('s'), rdflib.term.Variable('p')}}, 'expr': rdflib.term.Variable('__agg_2__'), 'var': rdflib.term.Variable('o'), '_vars': {rdflib.term.Variable('o'), rdflib.term.Variable('__agg_1__'), rdflib.term.Variable('__agg_2__'), rdflib.term.Variable('s'), rdflib.term.Variable('p')}}, 'PV': [rdflib.term.Variable('p'), rdflib.term.Variable('o')], '_vars': {rdflib.term.Variable('o'), rdflib.term.Variable('__agg_1__'), rdflib.term.Variable('__agg_2__'), rdflib.term.Variable('s'), rdflib.term.Variable('p')}}, 'datasetClause': None, 'PV': [rdflib.term.Variable('p'), rdflib.term.Variable('o')], '_vars': {rdflib.term.Variable('o'), rdflib.term.Variable('__agg_1__'), rdflib.term.Variable('__agg_2__'), rdflib.term.Variable('s'), rdflib.term.Variable('p')}}

[reeshabhranjan]

Me, @prince17080 and @guvi007 are inspecting this issue, we will get back to you if we find any solution.

[nicholascar]

@white-gecko can you please see if PR #1093 actually fixes this issue, as claimed by the PR raiser @devrb?