fetch-middleware.js

'use strict';

const fetch = require('./fetch');

module.exports = function fetchMW(req, res, next) {
  fetch(req.query.shape_id, (err, results) => {
    if (err) {
      return next(err);
    } else {
      req.dbResults = results;
      return next();
    }
  })
};

fetch.js

'use strict';
module.exports = fetch;

// use a prepared statement if using user input in the query to avoid SQL injection attacks!
const stmt = db.prepare('SELECT shape_pt_lat, shape_pt_lon FROM shapes where shape_id=?');
function fetch (shapeId, callback){ 
  const data = [];
  
  // this actually executes the query, and passes in the two callbacks defined below
  stmt.each([shapeId], addRow, onComplete);
  
  function onComplete(err, numRows) {
    if (err) {
      return callback(err);
    } else {
      return callback(null, data);
    }
  }
  
  function addRow(e, rows) => {
    if (e) {
      data.push(e); // probably want to do something other than just pushing the error onto the same array as the results
    } else {
      data.push({
        x: rows['shape_pt_lat'],
        y: rows['shape_pt_lon']
      });
    }
  }
}

mygist.js

'use strict';
const fetch = require('./fetch');

app.get('/data', (request, res) => {  
  res.setHeader("Access-Control-Allow-Origin",'http://localhost:8080');
  fetch(request, function(err, data){
    console.log(data, "dickt")
    if (err) {
      // do something about error - pass to err middleware with next(err) or send some kind of response
    } else {
        res.json(data);
    }
  });
});