how do i pass location coordinate getting from HTML5 & javascript to my rails controller and mongodb model ?

Question

I am working on a web app where I want to get user's current geolocation coordinates (Latitude. Longitude, Altitude). I am using Ruby on Rails with MongoDB (mongoid). I am getting users coordinate through HTML5 and Javascript.

for now I am displaying those coordinate in users/new.html.erb where I lodad a script in the head of new.html.erb such as

<!DOCTYPE html>
<html>
<head>
<script>
function getUserLocation() { 

//check if the geolocation object is supported, if so get position
if (navigator.geolocation)
    navigator.geolocation.getCurrentPosition(displayLocation, displayError);
else
    document.getElementById("locationData").innerHTML = "Sorry - your browser doesn't support geolocation!";
}

function displayLocation(position) { 

//build text string including co-ordinate data passed in parameter
var displayText = "User latitude is " + position.coords.latitude + " longitude is " + position.coords.longitude + " and altitude is " + position.coords.altitude;

var loc = [[position.coords.latitude, position.coords.longitude][position.coords.altitude]]

//display the string for demonstration
document.getElementById("locationData").innerHTML = displayText;
}
</script>

</head>

and in body tag I am requesting user to click on a button to get the cordinate display.

<input type="button" value="get location" onclick="getUserLocation()"/>
<div id="locationData">
Location Data
</div>

what I want to do is, transfer this location data (var loc) to my model places. The mongoid model is like below

model/place.rb

class Place
  include Mongoid::Document
   belongs_to :user
  embeds_one :location
  index({location: "2dsphere"})
end

model/location.rb

class Location
  include Mongoid::Document
   field :type, type: String
  field :coordinates, type: Array
  embedded_in :place

end

I want to know how can I pass javascript variable as a parameters to controller#new method and then to my model place where location is an embedded document.

Can someone please help with this?

Community · Accepted Answer · 2017-05-23 12:20:31Z

Got it resolved. Thanks to This answer

used the below code in script

 $.post('/places/create',{lat: position.coords.latitude, 
                            lng: position.coords.longitude, 
                            alt:position.coords.altitude });

and in controller

  def create
      @lng_lat = [params[:lng], params[:lat]]
      @alt = params[:alt]
      @place = Place.create(location:{type:"Point", coordinates:@lng_lat}, height:@alt)
    end

But, As I was using geospatial feature of MongoDB(Mongoid). After indexing coordinates "2dsphere". I was getting error: "failed with error 16755: "insertDocument :: caused by :: 16755 Can't extract geo keys from object, malformed geometry?:" This error occurs when we have "2dsphere" indexing for coordinates.

Then I changed params to float in controller before passing it to model, as i think cordinates from javascript where being passed as string. so changed the controller code to

 @lng_lat = [params[:lng].to_f, params[:lat].to_f]
  @alt = params[:alt].to_f

It worked perfectly fine.

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