https://github.com/paulmach/go.geojson

Encoding and decoding GeoJSON <-> Go
https://github.com/paulmach/go.geojson

decoding encoding geojson golang

Last synced: 15 days ago
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Encoding and decoding GeoJSON <-> Go

• Host: GitHub
• URL: https://github.com/paulmach/go.geojson
• Owner: paulmach
• License: mit
• Created: 2014-09-03T19:20:46.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2023-07-08T23:59:04.000Z (almost 2 years ago)
• Last Synced: 2025-04-07T21:13:35.751Z (about 2 months ago)
• Topics: decoding, encoding, geojson, golang
• Language: Go
• Size: 31.3 KB
• Stars: 304
• Watchers: 6
• Forks: 59
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# go.geojson [![CI](https://github.com/paulmach/go.geojson/workflows/CI/badge.svg)](https://github.com/paulmach/go.geojson/actions?query=workflow%3ACI+event%3Apush) [![Godoc Reference](https://godoc.org/github.com/paulmach/go.geojson?status.svg)](https://godoc.org/github.com/paulmach/go.geojson)

Go.geojson is a package for **encoding and decoding** [GeoJSON](http://geojson.org/) into Go structs.

Supports both the [json.Marshaler](http://golang.org/pkg/encoding/json/#Marshaler) and [json.Unmarshaler](http://golang.org/pkg/encoding/json/#Unmarshaler)

interfaces as well as [sql.Scanner](http://golang.org/pkg/database/sql/#Scanner) for directly scanning PostGIS query results.

The package also provides helper functions such as `UnmarshalFeatureCollection`, `UnmarshalFeature` and `UnmarshalGeometry`.

### Deprecated, use [orb/geojson](https://github.com/paulmach/orb/tree/master/geojson)

The [orb](https://github.com/paulmach/orb) package, and its subpackages, provide all the features here and more.

## Examples

* #### Unmarshalling  (JSON -> Go)

	go.geojson supports both the [json.Marshaler](http://golang.org/pkg/encoding/json/#Marshaler) and [json.Unmarshaler](http://golang.org/pkg/encoding/json/#Unmarshaler) interfaces as well as helper functions such as `UnmarshalFeatureCollection`, `UnmarshalFeature` and `UnmarshalGeometry`.

		// Feature Collection

		rawFeatureJSON := []byte(`

		  { "type": "FeatureCollection",

		    "features": [

		      { "type": "Feature",

		        "geometry": {"type": "Point", "coordinates": [102.0, 0.5]},

		        "properties": {"prop0": "value0"}

		      }

		    ]

		  }`)

		fc1, err := geojson.UnmarshalFeatureCollection(rawFeatureJSON)

		fc2 := geojson.NewFeatureCollection()

		err := json.Unmarshal(rawJSON, fc2)

		// Geometry

		rawGeometryJSON := []byte(`{"type": "Point", "coordinates": [102.0, 0.5]}`)

		g, err := geojson.UnmarshalGeometry(rawGeometryJSON)

		g.IsPoint() == true

		g.Point == []float64{102.0, 0.5}

* #### Marshalling (Go -> JSON)

		g := geojson.NewPointGeometry([]float64{1, 2})

		rawJSON, err := g.MarshalJSON()

		fc := geojson.NewFeatureCollection()

		fc.AddFeature(geojson.NewPointFeature([]float64{1,2}))

		rawJSON, err := fc.MarshalJSON()

* #### Scanning PostGIS query results

		row := db.QueryRow("SELECT ST_AsGeoJSON(the_geom) FROM postgis_table)

		var geometry *geojson.Geometry

		row.Scan(&geometry)

* #### Dealing with different Geometry types

	A geometry can be of several types, causing problems in a statically typed language.

	Thus there is a separate attribute on Geometry for each type.

	See the [Geometry object](https://godoc.org/github.com/paulmach/go.geojson#Geometry) for more details.

		g := geojson.UnmarshalGeometry([]byte(`

			{

	          "type": "LineString",

	          "coordinates": [

	            [102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [105.0, 1.0]

	          ]

	        }`))

		switch {

		case g.IsPoint():

			// do something with g.Point

		case g.IsLineString():

			// do something with g.LineString

		}

## Feature Properties

GeoJSON [Features](http://geojson.org/geojson-spec.html#feature-objects) can have properties of any type.

This can cause issues in a statically typed language such as Go.

So, included are some helper methods on the Feature object to ease the pain.

	// functions to do the casting for you

	func (f Feature) PropertyBool(key string) (bool, error) {

	func (f Feature) PropertyInt(key string) (int, error) {

	func (f Feature) PropertyFloat64(key string) (float64, error) {

	func (f Feature) PropertyString(key string) (string, error) {

	// functions that hide the error and let you define default

	func (f Feature) PropertyMustBool(key string, def ...bool) bool {

	func (f Feature) PropertyMustInt(key string, def ...int) int {

	func (f Feature) PropertyMustFloat64(key string, def ...float64) float64 {

	func (f Feature) PropertyMustString(key string, def ...string) string {