loopback-datatype-geopoint

Overview

The Geopoint object is a LoopBack data type that represents a physical location.

loopback-datasource-juggler and strong-remoting modules use this object to facilitate use of GeoPoint data type in a LoopBack model properties and remote methods.

Create a new GeoPoint object:

For example, to create a GeoPoint object in LoopBack:

var loopback = require(‘loopback’);
var here = new loopback.GeoPoint({lat: 10.32424, lng: 5.84978});

The constructor requires two values:

• lat: Latitude point in degrees. Range: -90 to 90.
• lng: Longitude point in degrees. Range: -180 to 180

Call the constructor with any of the following arguments:

• Two numbers, for example new GeoPoint(10.32, 5.84)
• Number string of form “lat, lng”, for example new GeoPoint('10.32, 5.84')
• Array with two number elements: [lat, lng], for example new GeoPoint([10.32, 5.84])
• Object with two number properties: lat and lng, for example new GeoPoint({ lat: 10.32, lng: 5.84})

Using GeoPoint type

In a LoopBack model, declare a GeoPoint property in the model JSON file, for example:

...
"properties": {
    "location": {
      "type": "GeoPoint"
    },
  ...
}
...

Or programmatically:

var CoffeeShop = loopback.createModel('coffee-shop', {
  location: 'GeoPoint'
});

In remote methods, set ‘accepts’ and ‘returns’ argument types for remote method to GeoPoint type; for example, in a remote method getNearbyLocation for model MyModel:

common/models/my-model.js

 MyModel.remoteMethod('getNearbyLocation', {
        accepts: {arg: 'loc', type: 'GeoPoint'},
        returns: {arg: 'location', type: 'GeoPoint'}
  });

API

GeoPoint.distanceBetween(pointA, pointB [, options])

This static method returns the spherical distance between two GeoPoints. The options object is optional.

For example:

loopback = require('loopback');
var here = new loopback.GeoPoint({ lat: 40.77492964101182, lng: -73.90950187151662});
var there = new loopback.GeoPoint({ lat: 40.7753227, lng: -73.909217 });

var distance = loopback.GeoPoint.distanceBetween(here, there);  // 0.03097916611592679

Arguments:

Options:

geoPoint.distanceTo(point, options)

This instance method returns the spherical distance to the given point. NOTE: The options object is required.

For example:

var loopback = require('loopback');

var here = new loopback.GeoPoint( {lat: 10, lng: 10} );
var there = new loopback.GeoPoint( {lat: 5, lng: 5} );

console.log( here.distanceTo( there, {type: 'miles'} ) ); // result: 486.3956513042483

Arguments:

geoPoint.toString()

This instance method returns a simple serialization of geoPoint.

For example:

var here = new loopback.GeoPoint({lat: 8, lng: 9});
console.log(here.toString());  

Output is:

8,9