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.
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.
});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 and the version
as follows by listening to the 'variables' and 'version' events:
sparqlXmlParser.parseXmlResultsStream(sparqlJsonResponseStream)
.on('variables', (variables: RDF.Variable[]) => console.log(variables))
.on('version', (version: string) => console.log(version))
.on('data', (bindings: IBindings) => { return; });
// This will output [ variable('book') ]The error thrown for unsupported versions can be skipped
by setting parseUnsupportedVersions to true when constructing the parser.
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 trueThis software is written by Ruben Taelman.
This code is released under the MIT license.