Rails PostGIS within_range query.

some_model.rb

def self.within_range(range_km, lat, lng)
  if lat.present? && lng.present?
    joins(location: :point)
      .where(
        "ST_DWithin(Geography(ST_MakePoint(longitude, latitude)),
                    Geography(ST_MakePoint(#{lng}, #{lat})),
                    #{(range_km * 1000).to_i})"
      )
  else
    none
  end
end