foo.js

import request from 'request'
import SparqlHttp from 'sparql-http-client'
 
const endpointUrl = process.env.MU_SPARQL_ENDPOINT !== undefined
    ? process.env.MU_SPARQL_ENDPOINT
    : 'http://database:8890/sparql'
 
function call(ctx, fn, query options) {
  return new Promise((resolve, reject) => {
    const requestCallback = (err, res) => {
      if (err) {
        reject(err)
      } else if (res.statusCode >= 300) {
        const err = new Error(`${res.statusCode} ${res.statusMessage}`)
        err.res = res
        reject(err)
      } else {
        resolve(res)
      }
    }

    return fn.call(ctx, query, requestCallback, options)
  })
}

export const endpoint = new SparqlHttp({
  request: SparqlHttp.requestModuleRequest(request),
  endpointUrl: endpointUrl,
  updateUrl: endpointUrl
})
 
export function constructQuery (query, options) {
  return call(endpoint, endpoint.constructQuery, query, options)
}
 
export function selectQuery (query, options) {
  return call(endpoint, endpoint.selectQuery, query, options)
}
 
export function updateQuery (query, options) {
  return call(endpoint, endpoint.updateQuery, query, options)
}