loopback-datatype-geopoint

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 & 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 programtically:

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

• in remote methods:

  'accepts' & 'returns' argument types, for remote method, can be set 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'}
    });
  

Static Method:

• distanceBetween(pointA, pointB, options):

  Determine the spherical distance between two GeoPoints

  Arguments:

  Name	Type	Description
  pointA	GeoPoint	Point A
  pointB	GeoPoint	Point B
  options	Object	Options object with one key, 'type'. See below.

  Options:

  Name	Type	Description
  type	String	Unit of measurement, one of: miles (default) radians kilometers meters miles feet degrees

Instance Methods:

• geoPoint.distanceTo(point, options):

  Determine the spherical distance to the given point.

  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: 438
  

  Arguments:

  Name	Type	Description
  point	GeoPoint	GeoPoint object to which to measure distance.
  options	Object	Options object with one key, 'type'. Same as options in distanceBetween()

• geoPoint.toString(): Simple serialization of geoPoint.