lakesuperior_legacy/lakesuperior/api/query.py

import logging

from io import BytesIO

from lakesuperior.dictionaries.namespaces import ns_collection as nsc
from lakesuperior.dictionaries.namespaces import ns_mgr as nsm
from lakesuperior.env import env
from lakesuperior.store.ldp_rs.lmdb_store import LmdbStore, TxnManager


logger = logging.getLogger(__name__)
rdfly = env.app_globals.rdfly
rdf_store = env.app_globals.rdf_store


def sparql_query(qry_str, fmt):
    '''
    Send a SPARQL query to the triplestore.

    @param qry_str (str) SPARQL query string. SPARQL 1.1 Query Language
    (https://www.w3.org/TR/sparql11-query/) is supported.
    @param fmt(string) Serialization format. This varies depending on the
    query type (SELECT, ASK, CONSTRUCT, etc.). [@TODO Add reference to RDFLib
    serialization formats]

    @return BytesIO
    '''
    with TxnManager(rdf_store) as txn:
        qres = rdfly.raw_query(qry_str)
        out_stream = BytesIO(qres.serialize(format=fmt))

    return out_stream