Sparqlxml-parse NPM

SPARQL-Results+XML Parse

A utility package that allows you to parse SPARQL XML results in a convenient RDF/JS-based datastructure.

For example, the following SPARQL XML result can be converted as follows:

In:

<?xml version="1.0"?>
<sparql xmlns="http://www.w3.org/2005/sparql-results#">
  <head>
    <variable name="book"/>
  </head>
  <results>
    <result>
      <binding name="book">
	      <uri>http://example.org/book/book1</uri>
      </binding>
    </result>
    <result>
      <binding name="book">
	      <uri>http://example.org/book/book2</uri>
      </binding>
    </result>
    <result>
      <binding name="book">
	      <uri>http://example.org/book/book3</uri>
      </binding>
    </result>
    <result>
      <binding name="book">
	      <uri>http://example.org/book/book4</uri>
      </binding>
    </result>
    <result>
      <binding name="book">
	      <uri>http://example.org/book/book5</uri>
      </binding>
    </result>
    <result>
      <binding name="book">
        <triple>
          <subject>
            <uri>http://example.org/bob</uri>
          </subject>
          <predicate>
            <uri>http://example.org/name</uri>
          </predicate>
          <object>
            <literal datatype='http://example.org/Type'>Bob</literal>
          </object>
        </triple>
      </binding>
    </result>
  </results>
</sparql>

Out:

[
  { '?book': namedNode('http://example.org/book/book1') },
  { '?book': namedNode('http://example.org/book/book2') },
  { '?book': namedNode('http://example.org/book/book3') },
  { '?book': namedNode('http://example.org/book/book4') },
  { '?book': namedNode('http://example.org/book/book5') }, 
  { '?book': quad(namedNode('http://example.org/bob'), namedNode('http://example.org/name'), literal('Bob', namedNode('http://example.org/Type'))) },
]

Where namedNode is an RDF/JS named node, quad is an RDF/JS quad/triple, and literal is an RDF/JS literal.

This library automatically converts all SPARQL XML result values to their respective RDFJS type.

Usage

Create a new parser

import {SparqlXmlParser} from "sparqlxml-parse";

const sparqlXmlParser = new SparqlXmlParser();

Optionally, you can provide a settings object to the constructor with optional parameters:

const sparqlXmlParser = new SparqlXmlParser({
  dataFactory: dataFactory, // A custom RDFJS datafactory
  prefixVariableQuestionMark: true, // If variable names in the output should be prefixed with '?', default is false.
});

Convert a SPARQL XML response stream

If you have many query results, then a streaming-based approach as provided by sparqlXmlParser.parseXmlResultsStream is ideal.

const sparqlJsonResponseStream = streamifyString(`<?xml version="1.0"?>
<sparql xmlns="http://www.w3.org/2005/sparql-results#">
  <head>
    <variable name="book"/>
  </head>
  <results>
    <result>
      <binding name="book">
        <uri>http://example.org/book/book1</uri>
      </binding>
    </result>
  </results>
</sparql>`);
sparqlXmlParser.parseXmlResultsStream(sparqlJsonResponseStream)
    .on('data', (bindings: IBindings) => console.log(bindings));
// This will output [ { '?book': namedNode('http://example.org/book/book1') } ]

Optionally, you can also retrieve the variables inside the head as follows by listening to the variables event:

sparqlXmlParser.parseXmlResultsStream(sparqlJsonResponseStream)
    .on('variables', (variables: RDF.Variable[]) => console.log(variables))
    .on('data', (bindings: IBindings) => { return; });
// This will output [ variable('book') ]

Convert a SPARQL XML boolean response stream

const sparqlJsonResponseStream = streamifyString(`<?xml version="1.0"?>
<sparql xmlns="http://www.w3.org/2005/sparql-results#">
  <boolean>true</boolean>
</sparql>`);
sparqlXmlParser.parseXmlBooleanStream(sparqlJsonResponseStream)
    .then((result: boolean) => console.log(result));
// This will output true