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May 10, 2017 12:11
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Federated queries with Virtuoso
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"""Federated queries with Virtuoso.""" | |
import sys | |
from SPARQLWrapper import SPARQLWrapper, JSON | |
QUERY_WIKIDATA = """ | |
PREFIX wd: <http://www.wikidata.org/entity/> | |
PREFIX wdt: <http://www.wikidata.org/prop/direct/> | |
SELECT ?work WHERE { | |
SERVICE <https://query.wikidata.org/sparql> { | |
SELECT ?work WHERE { | |
?work wdt:P50 wd:Q159552 . | |
} | |
} | |
} | |
""" | |
QUERY_DBPEDIA = """ | |
PREFIX dbo: <http://dbpedia.org/ontology/> | |
PREFIX dbr: <http://dbpedia.org/resource/> | |
SELECT ?work | |
WHERE { | |
SERVICE <http://DBpedia.org/sparql> { | |
SELECT ?work WHERE { | |
?work dbo:author dbr:Johannes_V._Jensen . | |
} | |
} | |
} | |
""" | |
QUERY_BOTH = """ | |
PREFIX wd: <http://www.wikidata.org/entity/> | |
PREFIX wdt: <http://www.wikidata.org/prop/direct/> | |
PREFIX dbo: <http://dbpedia.org/ontology/> | |
PREFIX dbr: <http://dbpedia.org/resource/> | |
SELECT ?work WHERE { | |
{ | |
SERVICE <https://query.wikidata.org/sparql> { | |
SELECT ?work WHERE { | |
?work wdt:P50 wd:Q159552 . | |
} | |
} | |
} | |
UNION | |
{ | |
SERVICE <http://DBpedia.org/sparql> { | |
SELECT ?work WHERE { | |
?work dbo:author dbr:Johannes_V._Jensen . | |
} | |
} | |
} | |
} | |
""" | |
query = QUERY_BOTH | |
if len(sys.argv) == 2: | |
if sys.argv[1] == 'wikidata': | |
query = QUERY_WIKIDATA | |
elif sys.argv[1] == 'dbpedia': | |
query = QUERY_DBPEDIA | |
else: | |
raise ValueError('input argument wrong') | |
sparql = SPARQLWrapper("http://127.0.0.1:8890/sparql") | |
sparql.setQuery(query) | |
sparql.setReturnFormat(JSON) | |
results = sparql.query().convert() | |
for result in results["results"]["bindings"]: | |
print(result) |
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There is a server error in your
QUERY_BOTH
. If you change the dbpedia service to tolower dbpedia in line 52 it works in 2022