Set geolocation in a global helper (Meteor)

Question

i try to set so geolocation informations in an helper. I use these packages:

mdg:geolocation, aldeed:geocoder

This is my helper:

Template.registerHelper("geo", function () {
  var geo = Geolocation.latLng() || { lat: 0, lng: 0 };

  if(geo.lat !== 0){
    var infos = Meteor.call('locationName', geo.lat, geo.lng, function(err, res){
        return res[0];
    });
  }
});

This is the object returned

And this is my server call

Meteor.methods({
  locationName: function(lat, lng){
  console.log(lat, lng);
  var geo = new GeoCoder({
    geocoderProvider: configs.geocoder.geocoderProvider,
    httpAdapter: configs.geocoder.httpAdapter,
    apiKey: configs.geocoder.apiKey
  });

  var reverseGeocoding = geo.reverse(lat, lng);

  return reverseGeocoding;
}
});

I tried a lot of thing but my {{geo.city}} is always empty. How can i structure it correctly?

Thank you

I think OP implies that `res[0]` contains the object which has the `city` property. — SylvainB, Aug 25 '15 at 15:22

score 0 · Answer 1 · edited May 23 '17 at 12:07

You are in a typical issue of method call within a helper. Look at your template helper's code. It basically does this:

Template.registerHelper("geo", function () {
  // inside helper
  // doing some stuff...
  Meteor.call('someMethod', function(err, res){
    // Other scope!
    console.log("Toto, I've a feeling we're not in the `geo` helper any more.");
    return res; // returning this to nowhere
  });
  // back inside helper
  return undefined; // returns before the above callback even triggers
});

The issue is that you cannot return something from a method call's callback and expect the helper from which you called that method to return this value: they're different scopes, because method calls are asynchronous. Here is what you can do:

Template.registerHelper("geo", function () {
  return Session.get('locationName');
});

updateLocationName = function (geo) {
  return Meteor.call('locationName', geo.lat, geo.lng, function(err, res){
        Session.set('locationName', res[0]);
  });
}

if (Meteor.isClient) {
  Meteor.startup(function () {
    var geo = Geolocation.latLng() || { lat: 0, lng: 0 };
    Session.setDefault('locationName', null);
    if(geo.lat !== 0){
      var infos = updateLocationName(geo);
    }
  });
}

If you want to update your session variable (inside an onRendered or autorun for example), you will just have to call updateLocationName() with an updated Geolocation.latLng() object.

It doesn't work. Thank you for your answer about the scope, i tried a lot of things... In Meteor.startup, the geo variable is set to { lat: 0, lng: 0 }. I need to set it at first load. — Mike Boutin, Aug 25 '15 at 17:58

score 0 · Answer 2 · answered Aug 25 '15 at 18:53

I made it worked, but maybe it have a better way to do it. Thank you for your answer! There's my code

Template.registerHelper("geo", function () {

if(Session.get('geolocation') === null){
    var geo = Geolocation.latLng() || { lat: 0, lng: 0 };

    if(geo.lat !== 0){
        Meteor.call('locationInfos', geo.lat, geo.lng, function(err, res){
            Session.set('geolocation', res[0]);
        });
    }
}

return Session.get('geolocation');

});

I set the session variable at NULL in Meteor.startup.

Set geolocation in a global helper (Meteor)

2 Answers2