如何在节点模块和另一个JavaScript文件中声明数组（Mongodb）

Question

I am very new to node.js and programming in general. I am trying to learn to retrieve a variable's value from Mongodb. I have the 'data' variable in my app.js

var data = require ("./public/assets/js/data.js");
app.get('/test', function(req, res) {
    res.locals.place = data;
    console.log(data);

    res.render('ViewMode');
});

my data.js file looks like this:

var mongoose = require ('mongoose');
var data = new Array();
mongoose.model('stories').find({},function(err, companies) {
    for (var i = 0; i < companies.length; i++) {
        data[i] = JSON.stringify(companies[i].place);
    }
});

module.exports = data;

and I want to use this in a JavaScript file I have for showing a map.

var places = []
var places =  locals.place;

for (var i = 0; i < places.length; i++) {
    var mylocation = places[i];
    var lat = mylocation.replace(/^\"\(([0-9-.]*),.*/g, "$1");
    var lng = mylocation.replace(/.*,\s*([0-9-.]*)\)\"$/g, "$1");
    var latLng = new google.maps.LatLng(lat, lng);
    var marker = new google.maps.Marker({
        position: latLng,
        map: map,
    });    
}  

I tried to use re.locals.variable but am not sure whether that's a right approach or not or do I need to have an ajax?

Thanks

Answer 1

Wrap the Mongo stuff in a function in your data.js module

var mongoose = require ('mongoose');

function getPlaces(callback){
  var data = new Array();
  // this function here is async, so use a callback to "return" the result
  mongoose.model('stories').find({},function(err, companies) {
    if(err){
      return callback(err, data);
    }
    for (var i = 0; i < companies.length; i++) {
      data[i] = JSON.stringify(companies[i].place);
    }
    return callback(null, data);
 });
}

// then export the function
module.exports = getPlaces;

Then require the module in express and pass a function to it

var placeFinder = require ("./public/assets/js/data.js");
app.get('/test', function(req, res){

  placeFinder(function(err, data){
    if(err){
      // Internal error!
      return res.send(500);
    }
    // your crazy code here to manipulate the data here

    res.locals.place = data;
    console.log(data);
    res.render('ViewMode');

  });
});