trifid-handler-sparql

SPARQL handler for Trifid. Fetches the graphs for a given IRI from a SPARQL endpoint.

Usage

The handler treats IRI that end with a slash as containers. Other IRIs are treated as resources. Before the actual triples are fetched an exists ASK query is issued. The ${iri} variable in the queries will be replaced with the requested IRI. The following options are supported:

• endpointUrl: The URL to the SPARQL endpoint
• resourceExistsQuery: The ASK query to check whether the resources exists or not
• resourceGraphQuery: The query to fetch the actual triples of the resource
• containerExistsQuery: The ASK query to check whether the container exists or not
• containerGraphQuery: The query to fetch the actual triples of the container
• resourceNoSlash: The handler will also check if there is a resource with a URL ending with a slash before running the container logic. Set this option to true to disable the resource exists query. Useful if you know there are no triples with container URLs.

Examples

Install this Trifid plugin using:

npm install trifid-handler-sparql

This configuration tells Trifid to use the trifid-handler-sparql handler and the DBpedia SPARQL endpoint. It also defines the queries to fetch the resources and containers:

middlewares:
  # […]
  sparql-handler:
    module: trifid-handler-sparql
    config:
      endpointUrl: https://dbpedia.org/sparql
      resourceExistsQuery: "ASK { <${iri}> ?p ?o }"
      resourceGraphQuery: "DESCRIBE <${iri}>"
      containerExistsQuery: "ASK { ?s a ?o. FILTER REGEX(STR(?s), \"^${iri}\") }"
      containerGraphQuery: "CONSTRUCT { ?s a ?o. } WHERE { ?s a ?o. FILTER REGEX(STR(?s), \"^${iri}\") }"

Debug

This package uses debug, you can get debug logging via: DEBUG=trifid:handler-sparql.