TheGeomGeoJSON

For PostGIS/PostgreSQL and ActiveRecord, provides the_geom_geojson getter and setter that update the_geom geometry(Geometry,4326) and the_geom_webmercator geometry(Geometry,3857) columns.

Web mapping libraries like Leaflet often don't support PostGIS's native Well-Known Binary (WKB) and Well-Known Text (WKT) representation, but they do support GeoJSON, so this library helps translate between the two.

• PostgreSQL >=9
• PostGIS 2.0.0 with support for JSON-C >= 0.9 compiled in
• ActiveRecord >=4
• if it exists, column the_geom must be WGS 84 SRID 4326
• if it exists, column the_geom_webmercator must be spherical mercator SRID 3857 (which is basically identical and should be used in preference to Google webmercator unofficial SRID 900913).

Per the commonly used CartoDB column naming convention, you have a table like:

CREATE TABLE pets (
  id                    serial primary key,
  the_geom              geometry(Geometry,4326),
  the_geom_webmercator  geometry(Geometry,3857)
)

You simply include it in your models:

class Pet < ActiveRecord::Base
  include TheGeomGeoJSON::ActiveRecord
end

Then:

[1] > jerry = Pet.create!
SQL (1.0ms)  INSERT INTO "pets" DEFAULT VALUES RETURNING "id"
=> #<Pet id: 1, the_geom: nil, the_geom_webmercator: nil>

[2] > jerry.the_geom_geojson = '{"type":"Point","coordinates":[-72.4861,44.1853]}'
=> "{\"type\":\"Point\",\"coordinates\":[-72.4861,44.1853]}"

[3] > jerry.save!
SQL (1.5ms)  UPDATE "pets" SET the_geom = ST_SetSRID(ST_GeomFromGeoJSON('{"type":"Point","coordinates":[-72.4861,44.1853]}'), 4326), the_geom_webmercator = ST_Transform(ST_SetSRID(ST_GeomFromGeoJSON('{"type":"Point","coordinates":[-72.4861,44.1853]}'), 4326), 3857) WHERE id = 1
Pet Load (0.3ms)  SELECT  "pets".* FROM "pets"  WHERE "pets"."id" = $1 LIMIT 1  [["id", 1]]
=> true

[4] > jerry.the_geom
=> "0101000020E61000007AA52C431C1F52C072F90FE9B7174640"

[5] > jerry.the_geom_webmercator
=> "0101000020110F0000303776EFFEC75EC11E1648AD64F55441"

If you see warnings like:

unknown OID 136825: failed to recognize type of 'the_geom'. It will be treated as String.

... then define the OID by creating config/initializers/active_record_postgis:

ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.tap do |klass|
  klass::OID.register_type('geometry', klass::OID::Identity.new)
end

1. It's hard to install PostGIS with JSON-C support on Mac OS X
2. The the_geom_geojson getter is rather inefficient - it's assumed you'll mostly use the setter

1. Fork it ( https://github.com/seamusabshere/the_geom_geojson/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Copyright 2014 Faraday