MeteorJS: Display Posts with locations within x miles of current location

Question

I am working on an application that will display the posts of people within a certain amount of distance of their location.

Whenever a post is created a value of location is created which is stored with: {"lat":39.7230949,"lng":-104.83521619999999}. The lat and longitude of the current location when the post was made.

This is from a function, Geolocation.latLng();, which prints out the object with the lat and lng of the current device.

I am now trying to figure out how to have the page which lists all the post, only show post that fall within a radius of the devices current location.

Here is my current function which lists all the post from my database.

Template.yakResults.searchResults = function () {
    var keyword  = Session.get("search-query");
    var query = new RegExp( keyword, 'i' );
    var results = Yaks.find( { $or: [{'yak': query}] }, {sort: {score: -1}});
    return {results: results};
}

What do I have to do to get the results to be with say 10 mile radius of the devices current long/lat which can be found with the function mentioned above.

I imagine I use an if statement of some sort or maybe a filer when I am finding the posts in the Yaks collection?

Does any one have any idea on how I can filter the collection of posts to do something similar to this?

If i need to post up more code to make it easier to understand my question please let me know and I will.

Answer 1

Figured it out. For any one who may be trying to do something similar in the future, here is what I did.

First I had have the posts location formatted to geoJSON before it could go into the database. Here is the code I used in order to achieve this.(NOTE: Gelocation.latLng(); function is from this meteor plugin(https://atmospherejs.com/mdg/geolocation)).

This is the code called whenever the yak is submitted.

Template.yaksSubmit.events({
'submit .yaksSubmitForm': function(event) {

        event.preventDefault();
        var yak = event.target.yak.value; //get yak input value
        var yakLocation = Geolocation.latLng(); // location of yak

        var lat = yakLocation.lat;

        var lng = yakLocation.lng;

        //check if the value is empty
        if(yak == "") {
            alert("You can't inert a empty yak!");
        } else {
            Meteor.call('yakInsert', yak, lng, lat);
            Router.go('yaksList');
        }
    }
});

Here is the yakInster method being called from my server.js file.

yakInsert: function(yak, lng, lat) {
    var postId = Yaks.insert({
        yak: yak,
        loc : {
            type: "Point",
            coordinates: [ lng, lat ]
        },
        score: 0,
        submitted: new Date(),
        user: Meteor.userId(),
        lng: lng,
        lat: lat
        // Geolocation.latLng(); JSON.stringify(yakLocation)
    });
}

Then I stored the devices long/lat in into a Session with a helper.

Template.yakResults.helpers({
lat: function() {
        var currentLocation = Geolocation.latLng(); // location of yak
        var lat = currentLocation.lat;
        Session.set("device-lat", lat);
    },
    lng: function() {
        var currentLocation = Geolocation.latLng(); // location of yak
        var lng = currentLocation.lng;
        Session.set("device-lng", lng);
    }
});

And then for my function to display all my posts I used the information explained in this blogpost on mongolab(http://blog.mongolab.com/2014/08/a-primer-on-geospatial-data-and-mongodb/). Here is what the function looks like

Template.yakResults.searchResults = function () {
    var lng = Session.get("device-lng");
    var lat = Session.get("device-lat");
    var query = new RegExp( keyword, 'i' );
    var results = Yaks.find( {
     loc:
       { $near :
          {
            $geometry:{ type:"Point", coordinates:[ lng, lat]},
            $minDistance: 0,
            $maxDistance: 5000
          }
       }
   });
    return {results: results};
}

This got the posts to display with their order determined by the location of each yak/post relative to the device's location.

the $minDistance & $maxDistance are in meters.

This might not be the best way to make it work but It worked for me. Just thought I would share it incase anybody else could use it.