distance_scopable.rb

module DistanceScopable
  extend ActiveSupport::Concern

  included do
    # Select a specified distance from the coordinate of the table (in meters)
    scope :distance_to_point, lambda { |table_name: self.table_name, srid: 4326, lat: nil, lng: nil, distance: 5000|
      fail 'Attributes missing' if distance.nil? || lat.nil? || lng.nil? || srid.nil?
      select(<<-SQL.squish
        ST_Distance(
             #{table_name}.coordinates,
             ST_GeographyFromText('SRID=#{srid};POINT(#{lng} #{lat})')
        ) as distance
        SQL
            )
    }

    scope :where_distance_within, lambda { |table_name: self.table_name, coordinate: {}, distance: 5000|
      fail 'Attributes missing' if distance.nil? || coordinate.nil? || coordinate.empty?
      where(<<-SQL.squish
        ST_DWithin(
          #{table_name}.coordinates,
          ST_GeographyFromText('SRID=#{coordinate[:srid]};POINT(#{coordinate[:lng]} #{coordinate[:lat]})'),
          #{distance}
        )
      SQL
     )
    }
  end
end