Extent PG array query in Rails

_pg_tag_usage.md

In Gemfile

gem 'pg_tag', git: 'git://gist.github.com/895e8e58ba83f72efd2a.git', require: 'pg_tag'

In rails model file

has_pg_tag **** # your col name

array.rb

class Array

  # Give %w[a b]
  # Return "'{a, b}'"
  #
  def to_pg_array_string
    "'{#{join(', ')}}'"
  end

  # Give %w[a b]
  # Return "ARRAY['a', 'b']"
  #
  def to_pg_array_text
    "ARRAY#{to_s}"
  end

  alias_method :to_pg_array_integer, :to_pg_array_text
end

pg_tag.gemspec

Gem::Specification.new do |s|
  s.name        = 'pg_tag'
  s.version     = '0.0.1'
  s.platform    = Gem::Platform::RUBY
  s.author      = 'Raykin'
  s.email       = 'raykincoldxiao@gmail.com'
  s.summary     = 'Easy query and update pg array column in rails'
  s.description = 'Same as Summary'
  s.files         = ['pg_tag.rb']
  s.require_path  = '.'
end

pg_tag.rb

require 'array'
require 'active_support/concern'

module PgTag

  def self.build_pg_string
    Proc.new do |ele, col_type|
      case ele
      when String, Numeric
        matchs = [ele]
      when Array
        matchs = ele
      else
        matchs = ele.to_a
      end
      matchs.send "to_pg_array_#{col_type}"
    end

  end

  extend ActiveSupport::Concern

  module ClassMethods

    def has_pg_tag(*names, col_type: :string)
      names.each do |name|
        define_singleton_method "#{name}_contain" do |match_value|
          pg_array = PgTag.build_pg_string.call(match_value, col_type)
          where("#{name} @> #{pg_array}")
        end

        define_singleton_method "#{name}_overlap" do |match_value|
          pg_array = PgTag.build_pg_string.call(match_value, col_type)
          where("#{name} && #{pg_array}")
        end

        define_method "add_#{name}" do |value|
          new_value = send(name).clone.push(value)
          send("#{name}=", new_value)
        end

      end
    end # END has_pg_tag

  end

end

ActiveRecord::Base.send :include, PgTag

pg_tag_test.rb

require 'minitest/autorun'
require 'active_record/railtie'
require 'pg_tag'

class PgTagTest < Minitest::Test

  def setup
    @str = "abc"
    @array = %w[1 2 3]
  end

  def test_str_to_pg_array
    assert_equal "'{abc}'", PgTag.build_pg_string.call(@str, 'string')
  end

  def test_array_to_pg_array
    assert_equal("ARRAY[\"1\", \"2\", \"3\"]",
                 PgTag.build_pg_string.call(@array, 'text'))
  end
end