polyfetcher

A Go Package can fetch polygon definitions from OpenStreet maps and it can also combine one or more polygons into one.

Overview

What it does?

• It can fetch Polygon definitions from OpenstreetMaps by taking an area name, throw error if the area is not in OSM database
• Combine one or more polygons into one single Multipolygon

Install

go get github.com/jinagamvasubabu/polyfetcher

How to use Fetch Polygons?

• get polyfetcher

  go get github.com/jinagamvasubabu/polyfetcher

• import and use it like below:

  import "github.com/jinagamvasubabu/polyfetcher"
  import "github.com/sirupsen/logrus"
 
  p := polyfetcher.GeometryUtils{}
  resp, err := p.FetchPolygons(context.Background(), []string{"germany", "belgium"})
  fmt.Println(resp)

How to use Combine Polygons?

• get polyfetcher

  go get github.com/jinagamvasubabu/polyfetcher

• import and use it like below:

  import "github.com/jinagamvasubabu/polyfetcher"
  import "github.com/sirupsen/logrus"
 
  p := polyfetcher.GeometryUtils{}
  resp, err := p.CombinePolygons(context.Background(), []string{"germany", "belgium"})
  fmt.Println(resp)

Response:

//GeoJson Open street map response structure
type GeoJson struct {
	Name        string        `json:"name"`
	Type        string        `json:"type"`
	Coordinates []interface{} `json:"coordinates"`
}

How to enable Debug logs?

• Pass logrus LogLevel:logrus.DebugLevel to GeometryUtils struct

  import "github.com/jinagamvasubabu/polyfetcher"

 
  p := polyfetcher.GeometryUtils{LogLevel:logrus.DebugLevel}
  resp, err := p.CombinePolygons(context.Background(), []string{"germany", "belgium"})

How to validate the data ?

Response type is schema.GeoJson, you can marshal the response to string and use geojsonlint to validate the geojson.

Note: If you get an error like Polygons and MultiPolygons should follow the right-hand rule then follow this below article to fix it. https://dev.to/jinagamvasubabu/solution-polygons-and-multipolygons-should-follow-the-right-hand-rule-2c8i

Errors:

• If one of the area is invalid area then it can fetch the other areas if they are valid
• If all areas which were passed are invalid then it will throw error error while fetching the polygon

Goroutines Support:

Goroutines support to fetch areas concurrently instead of synchronously

Author

JinagamVasubabu

License

Apache 2.0.