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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.