ingestor-metrolink/index.js

Simple script to get Metrolink tram station locations from the NaPTAN national transport dataset.

const { join } = require('path')
const { toJson } = require('xml2json')
const { readFile, writeFile } = require('fs')
const { ezThunk } = require('ez-promise')

const filename = join(__dirname + '/greater-manchester-transport-db.xml')
const read = ezThunk(readFile)
const write = ezThunk(writeFile)

module.exports = (outpath, inpath = filename) => read(inpath)
  .then(buffer => buffer.toString('utf8'))
  .then(toJson)
  .then(JSON.parse)
  .then(filterMetrolinkStationsOnly)
  .then(extractMetrolinkLocationData)
  .then(JSON.stringify)
  .then(saveResult(outpath))
  .then(onSuccess(outpath))
  .catch(onError)

function filterMetrolinkStationsOnly ({ NaPTAN: { StopPoints: { StopPoint } } }) {
  return StopPoint.filter(({ StopClassification: { StopType } }) => StopType === 'TMU')
}

function extractMetrolinkLocationData (stations) {
  return stations.map(({ Status: status, Descriptor: { CommonName: name, Street: street }, Place: { Location: { Translation: { Longitude: lng, Latitude: lat } } } }) => ({
    name, status, street, location: { lat,  lng }
  }))
}

function saveResult (outpath) {
  return result => {
    return write(outpath, result, 'utf8')
  }
}

function onSuccess (outpath) {
  return () => {
    console.log('Metrolink JSON output saved to \'%s\'', outpath)
  }
}

function onError (error) {
  console.log('Error saving Metrolink JSON:\n%s', error)
}