Helper to create a random identifier for a resource via Sparql.

sparql_unique_uri.py

from SPARQLWrapper import SPARQLWrapper, JSON, N3

exists = """
SELECT * 
WHERE {
OPTIONAL{<%(next_uri)s> ?p ?o}.
OPTIONAL{?s2 ?p2 <%(next_uri)s>}.
}

"""

def get_next_uri(namespace, endpoint, used_uris=[], max=99999, test=False):
    """
    Get the nextURI for the given namespace.

    SPARQL interpretation of getNextURI here:
    http://svn.code.sf.net/p/vivo/vitro/code/branches/dev-sdb/webapp/src/edu/cornell/mannlib/vitro/webapp/utils/jena/JenaIngestUtils.java

    """
    import random
    if not namespace.endswith('n'):
        namespace += 'n'
    count = 0
    while True:
        next_uri = namespace + str(random.randint(1000, max))
        q = exists % {'next_uri': next_uri}
        sparql = SPARQLWrapper(endpoint)
        sparql.setQuery(q)
        sparql.setReturnFormat(JSON)
        results = sparql.query().convert()
        if results['results']['bindings'][0] == {}:
            break
        count += 1
        if count == 10:
            raise Exception("""
                10 random uris were tried and none returned
                a unique uri.  Verify or increase max random uri.""")
    return next_uri


if __name__ == "__main__":
    from vivo_ingest.settings import NAMESPACE, VIVO_SPARQL
    print VIVO_SPARQL
    next = get_next_uri(NAMESPACE,
                        VIVO_SPARQL)
    print next