Add PostgreSQL support

.travis.yml

@@ -4,12 +4,18 @@ rvm:
   - 2.3
 sudo: required
 dist: trusty
+env: 
+  - DB=mysql
+  - DB=pg
+services:
+  - postgresql
 before_install: 
   - gem install bundler
   - gem update --system
   - gem --version
 before_script:
-  - mysql -u root -e 'CREATE DATABASE test;'
+  - mysql -u root -e 'CREATE DATABASE travis_ci_test;'
+  - psql -c 'create database travis_ci_test;' -U postgres
 gemfile:
   - gemfiles/3.2.gemfile
   - gemfiles/4.2.gemfile

README.md

@@ -56,7 +56,7 @@ Find then sort by hash mapping     1.120000   0.010000   1.130000 (  1.192891)
 
 ## Development
 
-After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test DB=mysql` / `rake test DB=pg` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
 

find_with_order.gemspec

@@ -30,8 +30,9 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler", "~> 1.11"
   spec.add_development_dependency "rake", "~> 12.0"
   spec.add_development_dependency "minitest", "~> 5.0"
+  spec.add_development_dependency "mysql2", ">= 0.3"
+  spec.add_development_dependency "pg", "~> 0.18"
 
   spec.add_dependency "rails", ">= 3"
-  spec.add_dependency "mysql2", ">= 0.3"
 
 end

gemfiles/3.2.gemfile

@@ -5,7 +5,10 @@ source 'https://rubygems.org'
 gem "activerecord", "~> 3.2"
 
 group :test do
-  gem 'mysql2' , '0.3.21'
+  case ENV['DB']
+  when "mysql"    ; gem 'mysql2' , '0.3.21'
+  when "postgres" ; gem 'pg', '~> 0.18'
+  end
   gem "simplecov"
   gem "codeclimate-test-reporter", "~> 1.0.0"
 end

gemfiles/4.2.gemfile

@@ -5,7 +5,10 @@ source 'https://rubygems.org'
 gem "activerecord", "~> 4.2"
 
 group :test do
-  gem 'mysql2' , '0.3.21'
+  case ENV['DB']
+  when "mysql"    ; gem 'mysql2' , '0.3.21'
+  when "postgres" ; gem 'pg', '~> 0.18'
+  end
   gem "simplecov"
   gem "codeclimate-test-reporter", "~> 1.0.0"
 end

gemfiles/5.0.gemfile

@@ -5,7 +5,10 @@ source 'https://rubygems.org'
 gem "activerecord", "~> 5.0"
 
 group :test do
-  gem 'mysql2' , '0.3.21'
+  case ENV['DB']
+  when "mysql"    ; gem 'mysql2' , '0.3.21'
+  when "postgres" ; gem 'pg', '~> 0.18'
+  end
   gem "simplecov"
   gem "codeclimate-test-reporter", "~> 1.0.0"
 end

lib/find_with_order.rb

@@ -1,16 +1,20 @@
 require "find_with_order/version"
+require "find_with_order/mysql_support"
+require "find_with_order/pg_support"
 require 'active_record'
 
 class << ActiveRecord::Base
   def find_with_order(ids)
     return none if ids.blank?
     ids = ids.uniq
-    return where(id: ids).order("field(#{table_name}.id, #{ids.join(',')})").to_a
+    return FindWithOrder::PGSupport.find_with_order(self, ids) if defined?(PG)
+    return FindWithOrder::MysqlSupport.find_with_order(self, ids)
   end
   def where_with_order(column, ids)
     return none if ids.blank?
     ids = ids.uniq
-    return where(column => ids).order("field(#{column}, #{ids.map(&:inspect).join(',')})")
+    return FindWithOrder::PGSupport.where_with_order(self, column, ids) if defined?(PG)
+    return FindWithOrder::MysqlSupport.where_with_order(self, column, ids)
   end
 end
 unless ActiveRecord::Base.respond_to?(:none) # extend only if not implement yet

lib/find_with_order/mysql_support.rb

@@ -0,0 +1,10 @@
+module FindWithOrder
+  module MysqlSupport
+    def self.find_with_order(relation, ids)
+      return relation.where(id: ids).order("field(#{relation.table_name}.id, #{ids.join(',')})").to_a
+    end
+    def self.where_with_order(relation, column, ids)
+      return relation.where(column => ids).order("field(#{column}, #{ids.map(&:inspect).join(',')})")
+    end
+  end
+end

lib/find_with_order/pg_support.rb

@@ -0,0 +1,26 @@
+module FindWithOrder
+  module PGSupport
+    def self.find_with_order(relation, ids)
+      # return relation.where(id: ids).order("array_position(ARRAY[#{ids.join(',')}], #{relation.table_name}.id)").to_a #array_position is only support in PG >= 9.5
+      return relation.where(id: ids)
+                     .joins("JOIN (SELECT id.val, row_number() over() FROM (VALUES(#{ids.join('),(')})) AS id(val)) AS id ON (#{relation.table_name}.id = id.val)")
+                     .order('row_number')
+    end
+    def self.where_with_order(relation, column, ids)
+      relation = relation.where(column => ids)
+      case ids.first
+      when Numeric
+        # return relation.order("array_position(ARRAY[#{ids.join(',')}], #{column})") #array_position is only support in PG >= 9.5
+        return relation.joins("JOIN (SELECT id.val, row_number() over() FROM (VALUES(#{ids.join('),(')})) AS id(val)) AS id ON (#{column} = id.val)")
+                       .order('row_number')
+      when String
+        ids.map!{|s| ActiveRecord::Base.connection.quote_string(s) }
+        # return relation.order("array_position(ARRAY['#{ids.join("','")}']::varchar[], #{column})") #array_position is only support in PG >= 9.5
+        return relation.joins("JOIN (SELECT id.val, row_number() over() FROM (VALUES('#{ids.join("'),('")}')) AS id(val)) AS id ON (#{column} = id.val)")
+                       .order('row_number')
+      else
+        raise "not support type: #{ids.first.class}"
+      end
+    end
+  end
+end

test/find_with_order_test.rb

@@ -1,4 +1,12 @@
 require 'test_helper'
+case ENV['DB']
+when 'mysql'
+  require 'mysql2_connection'
+when 'pg'
+  require 'postgresql_connection'
+else
+  raise "no database"
+end
 
 class FindWithOrderTest < Minitest::Test
   def setup
@@ -57,8 +65,8 @@ def test_association_find_with_order
 
   def test_ambiguous_id_in_join
     order = [2, 1, 3]
-    assert_equal order, User.joins(:posts).uniq.find_with_order(order).map(&:id)
-    assert_equal order, User.joins(:posts).uniq.where_with_order(:'users.id', order).pluck(:id)
+    assert_equal order, User.joins(:posts).find_with_order(order).map(&:id).uniq #postgresql doesn't support distinct + order
+    assert_equal order, User.joins(:posts).where_with_order(:'users.id', order).pluck(:id).uniq
   end
 end
 

test/mysql2_connection.rb

@@ -0,0 +1,5 @@
+ActiveRecord::Base.establish_connection(
+  "adapter"  => "mysql2",
+  "database" => "travis_ci_test",
+)
+require 'seeds'

test/postgresql_connection.rb

@@ -0,0 +1,5 @@
+ActiveRecord::Base.establish_connection(
+  "adapter"  => "postgresql",
+  "database" => "travis_ci_test",
+)
+require 'seeds'

test/test_helper.rb

@@ -5,9 +5,3 @@
 require 'find_with_order'
 
 require 'minitest/autorun'
-
-ActiveRecord::Base.establish_connection(
-  "adapter"  => "mysql2",
-  "database" => "test"
-)
-require 'seeds'