postgis_advanced_queries

🌐 Integrating PostGIS for Advanced Spatial Queries

Use PostgreSQL’s PostGIS extension for highly efficient geospatial indexing and queries. With ActiveRecord adapter and rgeo, you can store geometry columns and perform intersections, buffers, and nearest‐neighbor searches in SQL.

# migration
enable_extension 'postgis'

create_table :locations do |t|
  t.st_point :geom, geographic: true, null: false
  t.string  :name
end
add_index :locations, :geom, using: :gist

# app/models/location.rb
class Location < ApplicationRecord
  RGeo::ActiveRecord::SpatialFactoryStore.instance.tap do |config|
    config.default = RGeo::Geographic.spherical_factory(srid: 4326)
  end

  # Find locations within a 5km buffer
  scope :within_buffer, ->(lon, lat, km = 5) {
    point = RGeo::Geographic.spherical_factory(srid: 4326).point(lon, lat)
    where(%{
      ST_DWithin(
        geom,
        ST_GeogFromText('SRID=4326;POINT(%f %f)'),
        %d * 1000
      )
    } % [lon, lat, km])
  }
end

# Usage:
Location.within_buffer(-122.4194, 37.7749, 10)