Py SPARQL Transformer

Write your SPARQL query directly in the JSON-LD you would like to have in output.

Looking for the JavaScript Version?

News

• It is now possible to set a different merging anchor instead of id/@id using the $anchor modifier.

Table of Contents

• Motivation
• Query in JSON
• How to use
• Credits

Query in JSON

The core idea of this module is writing in a single file the query and the expected output in JSON.

Two syntaxes are supported: plain JSON and JSON-LD. Here the examples in the 2 formats for the query of cities.

• plain JSON

{
  "proto": [{
    "id" : "?id",
    "name": "$rdfs:label$required",
    "image": "$foaf:depiction$required"
  }],
  "$where": [
    "?id a dbo:City",
    "?id dbo:country dbr:Italy"
  ],
  "$limit": 100
}

• JSON-LD

{
  "@context": "http://schema.org/",
  "@graph": [{
    "@type": "City",
    "@id" : "?id",
    "name": "$rdfs:label$required",
    "image": "$foaf:depiction$required"
  }],
  "$where": [
    "?id a dbo:City",
    "?id dbo:country dbr:Italy"
  ],
  "$limit": 100
}

For the list of all properties and modifiers, read the full documentation.

How to use

Install by pip.

pip install SPARQLTransformer

Use in your JS application (node or browser).

from SPARQLTransformer import sparqlTransformer

out = sparqlTransformer(query, options)

The first parameter (query) is the query in the JSON format. The JSON can be:

• an already parsed (or defined real time) dict,
• the local path of a JSON file (that will then be read and parsed).

The options parameter is optional, and can define the following:

OPTION	DEFAULT	NOTE
context	http://schema.org/	The value in @context. It overwrites the one in the query.
sparqlFunction	None	A function receiving in input the transformed query in SPARQL, returning a Promise. If not specified, the module performs the query on its own1 against the specified endpoint.
endpoint	http://dbpedia.org/sparql	Used only if sparqlFunction is not specified.
debug	False	Enter in debug mode. This allow to print in console the generated SPARQL query.

See tests.py for further examples.

Credits

If you use this module for your research work, please cite:

Pasquale Lisena, Albert Meroño-Peñuela, Tobias Kuhn and Raphaël Troncy. Easy Web API Development with SPARQL Transformer. In 18th International Semantic Web Conference (ISWC), Auckland, New Zealand, October 26-30, 2019.

BIB file

Pasquale Lisena and Raphaël Troncy. Transforming the JSON Output of SPARQL Queries for Linked Data Clients. In WWW'18 Companion: The 2018 Web Conference Companion, April 23–27, 2018, Lyon, France. https://doi.org/10.1145/3184558.3188739

BIB file