initialBindings in combination with named graph

[ddeboer]

Issue type:

• 🐛 Bug

---

Description:

This query works fine:

CONSTRUCT FROM <http://www.ontotext.com/retain-bind-position> WHERE { ?s ?p ?o }  LIMIT 100

With code:

const quadStream = await this.engine.queryQuads(query, {
  sources: [
        {
          type: 'sparql',
          value: 'https://www.goudatijdmachine.nl/sparql/repositories/gtm',
        },
      ],
});

But when adding initial bindings, we get an error:

const quadStream = await this.engine.queryQuads(query, {
  sources: [
        {
          type: 'sparql',
          value: 'https://www.goudatijdmachine.nl/sparql/repositories/gtm',
        },
      ],
  initialBindings: bindingsFactory.fromRecord({}) as unknown as Bindings,
});

Conversely, when we’re not querying named graphs, the initial bindings work fine:

CONSTRUCT WHERE { ?s ?p ?o } LIMIT 100

---

Environment:

@comunica/query-sparql@2.6.6

Crash log:

Cannot read properties of undefined (reading '0')","stack":"TypeError: Cannot read properties of undefined (reading '0')\n    at translateFrom (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/sparqlalgebrajs/lib/sparql.js:228:32)\n    at translateOperation (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/sparqlalgebrajs/lib/sparql.js:71:33)\n    at translateProject (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/sparqlalgebrajs/lib/sparql.js:369:41)\n    at translateOperation (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/sparqlalgebrajs/lib/sparql.js:82:36)\n    at toSparqlJs (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/sparqlalgebrajs/lib/sparql.js:48:18)\n    at toSparql (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/sparqlalgebrajs/lib/sparql.js:42:32)\n    at ActorQueryOperationSparqlEndpoint.run (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/@comunica/actor-query-operation-sparql-endpoint/lib/ActorQueryOperationSparqlEndpoint.js:75:52)\n    at ActorQueryOperationSparqlEndpoint.runObservable (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/@comunica/core/lib/Actor.js:57:29)\n    at MediatorNumber.mediate (/Users/david/src/netwerk-digitaal-erfgoed/network-of-terms/node_modules/@comunica/core/lib/Mediator.js:79:22)\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)","path":["terms"],"locations":[{"line":2,"column":3}],"extensions":{}},"message":"Cannot read properties of undefined (reading '0')"}

---

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[github-actions]

Thanks for reporting!

[rubensworks]

A bounty has been placed on this issue via the Comunica Association (see original post).

I suspect this is just a small issue in https://github.com/joachimvh/SPARQLAlgebra.js related to this call: https://github.com/comunica/comunica/blob/master/packages/bus-query-operation/lib/Bindings.ts#L41

[simonvbrae]

This issue has been fixed in the following commit:
joachimvh/SPARQLAlgebra.js@edfbb30

[rubensworks]

🎉

[rubensworks]

We'll bump the sparqlalgebra version in a next version of comunica.