SPARQL.js – A SPARQL 1.1 parser for JavaScript

The SPARQL 1.1 Query Language allows to query datasources of RDF triples. SPARQL.js translates SPARQL into JSON and back, so you can parse and build SPARQL queries in your JavaScript applications. It also contains support for the SPARQL* extension under the sparqlStar option.

It fully supports the SPARQL 1.1 specification, including property paths, federation, and updates.

Usage

Library

// Parse a SPARQL query to a JSON object
var SparqlParser = require('sparqljs').Parser;
var parser = new SparqlParser();
var parsedQuery = parser.parse(
  'PREFIX foaf:  ' +
  'SELECT * { ?mickey foaf:name "Mickey Mouse"@en; foaf:knows ?other. }');

// Regenerate a SPARQL query from a JSON object
var SparqlGenerator = require('sparqljs').Generator;
var generator = new SparqlGenerator({ /* prefixes, baseIRI, factory, sparqlStar */ });
parsedQuery.variables = ['?mickey'];
var generatedQuery = generator.stringify(parsedQuery);

Set sparqlStar to true to allow SPARQL* syntax.

Set pathOnly to true to parse SPARQL paths such as foaf:name/foaf:knows rather than the full SPARQL Algebra.

Validation

By default SPARQL.js throws on queries that are syntactically correct, but not allowed by the spec. Set skipValidation to true to skip validation.

// Parse a SPARQL query without validation.
var SparqlParser = require('sparqljs').Parser;
var parser = new SparqlParser({ skipValidation: true });
var parsedQuery = parser.parse(
  'select (?x as ?xString)' +
  '(count(?y) as ?count)' +
  '{ ?x ?y ?z }');

Standalone

$ sparql-to-json --strict query.sparql

Parse SPARQL* syntax by default. For pure SPARQL 1.1, use the --strict flag.

Representation

Queries are represented in a JSON structure. The most easy way to get acquainted with this structure is to try the examples in the queries folder through sparql-to-json. All examples of the SPARQL 1.1 specification have been included, in case you wonder how a specific syntactical construct is represented.

Here is a simple query in SPARQL:

PREFIX dbpedia-owl: 
SELECT ?p ?c WHERE {
    ?p a dbpedia-owl:Artist.
    ?p dbpedia-owl:birthPlace ?c.
    ?c  "York"@en.
}

And here is the same query in JSON:

{
  "queryType": "SELECT",
  "variables": [
    {
      "termType": "Variable",
      "value": "p"
    },
    {
      "termType": "Variable",
      "value": "c"
    }
  ],
  "where": [
    {
      "type": "bgp",
      "triples": [
        {
          "subject": {
            "termType": "Variable",
            "value": "p"
          },
          "predicate": {
            "termType": "NamedNode",
            "value": "https://www.w3.org/1999/02/22-rdf-syntax-ns#type"
          },
          "object": {
            "termType": "NamedNode",
            "value": "https://dbpedia.org/ontology/Artist"
          }
        },
        {
          "subject": {
            "termType": "Variable",
            "value": "p"
          },
          "predicate": {
            "termType": "NamedNode",
            "value": "https://dbpedia.org/ontology/birthPlace"
          },
          "object": {
            "termType": "Variable",
            "value": "c"
          }
        },
        {
          "subject": {
            "termType": "Variable",
            "value": "c"
          },
          "predicate": {
            "termType": "NamedNode",
            "value": "https://xmlns.com/foaf/0.1/name"
          },
          "object": {
            "termType": "Literal",
            "value": "York",
            "language": "en",
            "datatype": {
              "termType": "NamedNode",
              "value": "https://www.w3.org/1999/02/22-rdf-syntax-ns#langString"
            }
          }
        }
      ]
    }
  ],
  "type": "query",
  "prefixes": {
    "dbpedia-owl": "https://dbpedia.org/ontology/"
  }
}

The representation of triples uses the RDF/JS representation.

Installation

$ [sudo] npm [-g] install sparqljs

License, status and contributions

The SPARQL.js library is copyrighted by Ruben Verborgh and released under the MIT License.

Contributions are welcome, and bug reports or pull requests are always helpful.

Contributors

• Thanks to Tim Ermilov for driving the SPARQL generator