node-red-contrib-sparql

A Node-RED node for executing SPARQL queries against SPARQL endpoints, implementing the W3C SPARQL 1.1 Protocol. Based on sparql-http-client.

Features

• Execute SELECT, CONSTRUCT, DESCRIBE, ASK, and UPDATE SPARQL queries
• Supports all three W3C SPARQL Protocol HTTP methods: POST (direct), POST (form-encoded), and GET
• HTTP Basic Authentication support
• Configurable query timeout
• Multiple output formats: simplified bindings, flat values, or full SPARQL JSON response
• Dynamic query and endpoint injection via incoming messages

Nodes

sparql-query

Executes a SPARQL query against a configured endpoint.

Inputs:

| Property | Type | Description | |----------|------|-------------| | msg.query | string | SPARQL query (highest priority, overrides node config) | | msg.payload | string | Used as query if msg.query is not set | | msg.endpoint | string | Endpoint URL (overrides configured endpoint) |

Outputs:

| Property | Type | Description | |----------|------|-------------| | msg.payload | array/boolean/string/object | Query results | | msg.queryType | string | Detected query type (SELECT, CONSTRUCT, DESCRIBE, ASK, UPDATE) | | msg.sparqlQuery | string | The executed query |

Output formats (configurable):

| Format | SELECT result | ASK result | |--------|--------------|------------| | JSON (simplified) | results.bindings array with type metadata | boolean | | JSON (flat values) | Array of { var: "value" } objects (no type info) | boolean | | JSON (full response) | Complete SPARQL JSON Results object | Complete response |

CONSTRUCT/DESCRIBE always return RDF text. UPDATE always returns { success: true }.

sparql-endpoint (config node)

Configures a reusable SPARQL endpoint connection.

| Property | Description | |----------|-------------| | Endpoint | SPARQL endpoint URL | | HTTP Method | POST (direct), POST (form-encoded), or GET | | Username / Password | Optional HTTP Basic Authentication credentials |

Example

Import the example flow from examples/basic-select.json via the Node-RED import menu.

Requirements

• Node.js >= 18.0.0
• Node-RED >= 2.0.0

License

MIT