graphql-geojson-resolver-ex.js

// mock data
const data = [
  { vehicleid: 1, latitude: 40.1, longitude: -76.5 },
  { vehicleid: 2, latitude: 40.2, longitude: -76.6 },
  { vehicleid: 3, latitude: 40.3, longitude: -76.7 }
]

const resolvers = {
  Coordinates: new GraphQLScalarType({
    name: 'Coordinates',
    description: 'A set of coordinates. x, y',
    parseValue(value) {
      return value;
    },
    serialize(value) {
      return value;
    },
    parseLiteral(ast) {
      return ast.value;
    },
  }),
  PointGeometry: {
    type() {
      return 'Point';
    },
    coordinates(item) {
      return [item.longitude, item.latitude];
    },
  },
  PointProps: {
    id(item) {
      return item.vehicleid;
    },
    lat(item) {
      return item.latitude;
    },
    lon(item) {
      return item.longitude;
    },
  },
  PointObject: {
    type() {
      return 'Feature';
    },
    geometry(item) {
      return item;
    },
    properties(item) {
      return item;
    },
  },
  FeatureCollection: {
    type() {
      return 'FeatureCollection';
    },
    features(data) {
      return data
    },
  },
  Query: {
    transit_feed(_, args, ctx) {
      // make your async call for data here
      return data;
    },
  },
};