CODEWITHSUNDEEP
pythonescapingcharactersparqldbpedia
Sheltine
Sheltine

Reputation: 29

How to escape special characters in SPARQL Prefixed Names?

I'm making requests to DBPedia using SPARQL and Python.

Sadly, I'm always getting an error when I send requests with special characters (like parenthesis).

I tried to escape it with backslashes (as in code below) but it's not working.

I read that I could specify the entire URI but it doesn't work either (but I might have not done it the right way).

Does anybody have another option or could provide an example of how I can write my request with the entire URI, considering the request I already have?

query = """
    PREFIX : <http://dbpedia.org/resource/>
    SELECT DISTINCT ?s ?p ?o WHERE {
       {
           ?s ?p ?o
           FILTER (?s=:Grimaldi_\(crater\))

       }
    }
    """

Here is the error I get:

QueryBadFormed: QueryBadFormed: a bad request has been sent to the endpoint, probably the sparql query is bad formed.

Response: b"Virtuoso 37000 Error SP030: SPARQL compiler, line 0: Bad character '\\' (0x5c) in SPARQL expression at '\\'\n\nSPARQL query:\n\n#output-format:application/sparql-results+json\n\n PREFIX : <http://dbpedia.org/resource/>\nSELECT DISTINCT ?s ?p ?o WHERE {\n {\n ?s ?p ?o\n FILTER (?s=:Grimaldi_\\(crater\\))\n\n }\n}\n"

Upvotes: 1

Views: 1303

Answers (2)

Kingsley Uyi Idehen
Kingsley Uyi Idehen

Reputation: 925

We have fixed this issue (which was specific to the 7.x rather than the more recent 8.x release) and applied it to the Virtuoso instances behind the DBpedia-Snapshot and DBpedia-Live instances.

Query:

PREFIX : <http://dbpedia.org/resource/>
SELECT DISTINCT ?s ?p ?o WHERE {
       {
           ?s ?p ?o
           FILTER (?s=:Grimaldi_\(crater\))

       }
    }

Live DBpedia-Snapshot SPARQL Query Definition: Link

Live DBpedia-Live SPARQL Query Definition: Link

Another example based on a comma (,) in the url. Note the original query has been changed to add the backslash (\) in order for it to work.

Query:

PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX dbp: <http://dbpedia.org/property/>
PREFIX dbr: <http://dbpedia.org/resource/>
PREFIX grs: <http://www.georss.org/georss/>
PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#>

SELECT ?label ?country ?isPartOf ?_type ?capital ?lcity ?geopoint
WHERE {
        { dbr:Eraring\,_New_South_Wales rdfs:label ?label  .  FILTER(LANGMATCHES(LANG(?label), "en"))}
          UNION{OPTIONAL{dbr:Eraring\,_New_South_Wales dbo:country ?country} }
          UNION{OPTIONAL{dbr:Eraring\,_New_South_Wales dbo:isPartOf ?isPartOf}}
          UNION{OPTIONAL{dbr:Eraring\,_New_South_Wales <http://purl.org/linguistics/gold/hypernym> ?_type}}
          UNION{OPTIONAL{dbr:Eraring\,_New_South_Wales dbo:capital ?capital}}
          UNION{OPTIONAL{dbr:Eraring\,_New_South_Wales dbo:largestCity ?lcity}}
          UNION{OPTIONAL{dbr:Eraring\,_New_South_Wales grs:point ?geopoint}}
  }

Live SPARQL Query Definition: Link

Upvotes: 1

TallTed
TallTed

Reputation: 9434

The full URI definitely works, as --

SELECT DISTINCT ?s ?p ?o WHERE {
   {
       ?s ?p ?o
       FILTER ( ?s = <http://dbpedia.org/resource/Grimaldi_(crater)> )
   }
}

There is an open bug in Virtuoso v7's handling of Prefixed Names with backslash escaping (such as your :Grimaldi_\(crater\) with PREFIX : <http://dbpedia.org/resource/>, or the more common dbr:Grimaldi_\(crater\) with PREFIX dbr: <http://dbpedia.org/resource/>). Please add your voice to the github issue, to help raise its priority.

The backslash-escaping in prefixed names now works as it should in Virtuoso 7 (07.20.3230, as of commit 5f68a2e2f2, 2019-04-01), which backs the DBpedia instance.

Upvotes: 3

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