@optional bugged about graphql-ld.js HOT 4 OPEN

"graphql-ld": "^1.4.0",
"graphql-ld-comunica": "^1.2.1",

var Client = require("graphql-ld").Client;
const QueryEngineComunica = require('graphql-ld-comunica').QueryEngineComunica;

main();

async function main() {
// Define a JSON-LD context
  const context = {
    "@context":           {
      "type": "http://www.w3.org/1999/02/22-rdf-syntax-ns#type",
      "rdfs": "http://www.w3.org/2000/01/rdf-schema#",
      "owl": "http://www.w3.org/2002/07/owl#",
      "label": "rdfs:label",
      "comment": "rdfs:comment",
      "domain": "rdfs:domain",
      "range": "rdfs:range",
      "DatatypeProperty": "owl:DatatypeProperty"
    }
  };

// Create a GraphQL-LD client based on a client-side Comunica engine over 2 sources
  const comunicaConfig = {
    sources: ["http://localhost:8080/rml.ttl"],
  };
  const client = new Client({context, queryEngine: new QueryEngineComunica(comunicaConfig)});

// Define a query
  const query = `
              {
              id @single
              type (_:DatatypeProperty)
              label @single
              comment @single
              domain @optional
              range @optional
            }`;

// Execute the query
  const {data} = await client.query({query});

  console.log(data);
}

@prefix cc:			<http://creativecommons.org/ns#> .
@prefix dcterms:		<http://purl.org/dc/terms/> .
@prefix xsd: 			<http://www.w3.org/2001/XMLSchema#> .
@prefix owl: 			<http://www.w3.org/2002/07/owl#> .
@prefix foaf: 			<http://xmlns.com/foaf/0.1/> .
@prefix ql: 			<http://semweb.mmlab.be/ns/ql#> .
@prefix rml: 			<http://semweb.mmlab.be/ns/rml#> .
@prefix rmlt: 			<http://semweb.mmlab.be/ns/rml-target#> .
@prefix rr: 			<http://www.w3.org/ns/r2rml#> .
@prefix rdf: 			<http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: 			<http://www.w3.org/2000/01/rdf-schema#> .
@prefix vann: 			<http://purl.org/vocab/vann/> .
@prefix xml: 			<http://www.w3.org/XML/1998/namespace> .
@prefix : 	    		<http://semweb.mmlab.be/ns/rml#> .
@base 		    		<http://semweb.mmlab.be/ns/rml#> .

###  http://semweb.mmlab.be/ns/rml#iterator

rml:iterator rdf:type owl:DatatypeProperty ;
    rdfs:label   "iterator" ;
    rdfs:comment "an expression qualified according to the reference formulation specified for pointing to an extract of the source data. "@en ;
    rdfs:domain  rml:LogicalSource;
    rdfs:range   xsd:string .


###  http://semweb.mmlab.be/ns/rml#reference

rml:reference rdf:type owl:DatatypeProperty ;
    rdfs:label   "reference" ;
    rdfs:comment "A valid expression that selects values from the source data. The reference should confront to the syntax rules/grammar of the specified Reference Formulation. "@en ;
    rdfs:domain  rr:TermMap;
    rdfs:range   xsd:string .


###  http://semweb.mmlab.be/ns/rml#version

rml:version rdf:type owl:DatatypeProperty ;
    rdfs:label   "version" ;
    rdfs:comment "It defines the version of the reference Formulation used. "@en ;
    rdfs:domain  rml:LogicalSource;
    rdfs:range   xsd:string .

###  http://semweb.mmlab.be/ns/rml#source

rml:source rdf:type rdf:Property ;
    rdfs:label   "source" ;
    rdfs:comment "qualified name of the source data."@en ;
    rdfs:domain  rml:LogicalSource .


###  http://mmlab.be/rml#query

rml:query rdf:type owl:DatatypeProperty ;
    rdfs:comment "A valid query."@en ;
    rdfs:domain  rml:LogicalSource .