---
title: "Rails 6 adds implicit_order_column"
description:
  "Rails 6 adds implicit_order_column for ordering records implicitly"
canonical_url: "https://www.bigbinary.com/blog/rails-6-adds-implicit_order_column"
markdown_url: "https://www.bigbinary.com/blog/rails-6-adds-implicit_order_column.md"
---

# Rails 6 adds implicit_order_column

Rails 6 adds implicit_order_column for ordering records implicitly

- Author: Amit Choudhary
- Published: April 16, 2019
- Categories: Rails 6, Rails

Rails 6 added [implicit_order_column](https://github.com/rails/rails/pull/34480)
on `ActiveRecord::ModelSchema` which allows us to define a custom column for
implicit ordering on the model level. If there is no `implicit_order_column`
defined, Rails takes a primary key as the implicit order column. Also, before
Rails 6, the primary key was used to order records implicitly by default.

This has impact on methods like
[first](https://api.rubyonrails.org/v5.2/classes/ActiveRecord/FinderMethods.html#method-i-first)
,
[last](https://api.rubyonrails.org/v5.2/classes/ActiveRecord/FinderMethods.html#method-i-last)
and
[many more](https://edgeapi.rubyonrails.org/classes/ActiveRecord/FinderMethods.html)
where implicit ordering is used.

Let's checkout how it works.

#### Rails 5.2

```ruby
>> class User < ApplicationRecord
>>   validates :name, presence: true
>> end

=> {:presence=>true}

>> User.first
SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT $1  [["LIMIT", 1]]

=> #<User id: 1, name: "Amit", created_at: "2019-03-11 00:18:41", updated_at: "2019-03-11 00:18:41">

>> User.last
SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT $1  [["LIMIT", 1]]

=> #<User id: 2, name: "Mark", created_at: "2019-03-11 00:20:42", updated_at: "2019-03-11 00:20:42">

>> class User < ApplicationRecord
>>   validates :name, presence: true
>>   self.implicit_order_column = "updated_at"
>> end

=> Traceback (most recent call last):
        2: from (irb):10
        1: from (irb):12:in '<class:User>'
NoMethodError (undefined method 'implicit_order_column=' for #<Class:0x00007faf4d6cb408>)
```

#### Rails 6.0.0.beta2

```ruby
>> class User < ApplicationRecord
>>   validates :name, presence: true
>> end

=> {:presence=>true}

>> User.first
SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT $1  [["LIMIT", 1]]

=> #<User id: 1, name: "Amit", created_at: "2019-03-11 00:18:41", updated_at: "2019-03-11 00:18:41">

>> User.last
SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT $1  [["LIMIT", 1]]

=> #<User id: 2, name: "Mark", created_at: "2019-03-11 00:20:42", updated_at: "2019-03-11 00:20:42">

>> class User < ApplicationRecord
>>   validates :name, presence: true
>>   self.implicit_order_column = "updated_at"
>> end

=> "updated_at"

>> User.find(1).touch
SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
UPDATE "users" SET "updated_at" = $1 WHERE "users"."id" = $2  [["updated_at", "2019-03-11 00:23:33.369021"], ["id", 1]]

=> true

>> User.first
SELECT "users".* FROM "users" ORDER BY "users"."updated_at" ASC LIMIT $1  [["LIMIT", 1]]

=> #<User id: 2, name: "Mark", created_at: "2019-03-11 00:20:42", updated_at: "2019-03-11 00:23:09">

>> User.last
SELECT "users".* FROM "users" ORDER BY "users"."updated_at" DESC LIMIT $1  [["LIMIT", 1]]

=> #<User id: 1, name: "Amit", created_at: "2019-03-11 00:18:41", updated_at: "2019-03-11 00:23:33">

```

Here is the relevant [pull request](https://github.com/rails/rails/pull/34480).

## Links

- [Human page](https://www.bigbinary.com/blog/rails-6-adds-implicit_order_column)