SELECT queries

SELECT queries return tabular data with named variables. sparqlite returns the standard SPARQL JSON results format as a Python dictionary.

Basic SELECT query

from sparqlite import SPARQLClient

with SPARQLClient("https://opencitations.net/meta/sparql") as client:
    result = client.query("""
        PREFIX fabio: <http://purl.org/spar/fabio/>
        PREFIX dcterms: <http://purl.org/dc/terms/>

        SELECT ?article ?title WHERE {
            ?article a fabio:JournalArticle ;
                     dcterms:title ?title .
        }
        LIMIT 10
    """)

    for row in result["results"]["bindings"]:
        print(f"Article: {row['article']['value']}")
        print(f"Title: {row['title']['value']}")

Result structure

The returned dictionary follows the SPARQL JSON results format:

with SPARQLClient("https://opencitations.net/meta/sparql") as client:
    result = client.query("""
        PREFIX fabio: <http://purl.org/spar/fabio/>
        PREFIX dcterms: <http://purl.org/dc/terms/>

        SELECT ?article ?title WHERE {
            ?article a fabio:JournalArticle ;
                     dcterms:title ?title .
        }
        LIMIT 10
    """)

    # Get variable names
    print(f"Variables: {result['head']['vars']}")  # ['article', 'title']

    # Get the number of rows
    print(f"Found {len(result['results']['bindings'])} results")

    # Check if there are any results
    if result["results"]["bindings"]:
        print("Query returned results")

Handling missing values

When a variable is unbound in a result row (OPTIONAL), it is absent from the binding:

with SPARQLClient("https://opencitations.net/meta/sparql") as client:
    result = client.query("""
        PREFIX fabio: <http://purl.org/spar/fabio/>
        PREFIX dcterms: <http://purl.org/dc/terms/>
        PREFIX prism: <http://prismstandard.org/namespaces/basic/2.0/>

        SELECT ?article ?title ?date WHERE {
            ?article a fabio:JournalArticle ;
                     dcterms:title ?title .
            OPTIONAL { ?article prism:publicationDate ?date }
        }
        LIMIT 5
    """)

    for row in result["results"]["bindings"]:
        title = row["title"]["value"]
        if "date" in row:
            print(f"{title} was published on {row['date']['value']}")
        else:
            print(f"{title} has no publication date recorded")

Using the select() alias

The select() method is an alias for query():

with SPARQLClient("https://opencitations.net/meta/sparql") as client:
    # These are equivalent
    result = client.query(query)
    result = client.select(query)