Modify Ruby on Rails ActiveRecord Default Primary Keys from BIGINT to INTEGER

why it’s?

Rails5.1 or later is Breaking Changed ActiveRecord Default Primary Keys to BIGINT on MySQL and PostgreSQL. here a reset the Default Primary Key to an INTEGER.

Rails5.1 ReleaseNote

Ruby on Rails 5.1 Release Notes - Ruby on Rails Guides

Change Default Primary Keys to BIGINT. (Pull Request)

Change Default Primary Keys to BIGINT by jmccartie · Pull Request #26266 · rails/rails

Why to switch back to integer from Bigint?

I think that Bigint is OK in the new Rails Project,
I think that there are many disadvantages when becoming Bigint when creating a new ActiveRecord model with an existing project created before Rails 5.1.

How to

modify application model generator config

module ExampleApp
  class Application < Rails::Application  
   config.generators do |generator|
     generator.orm :active_record, primary_key_type: :integer
   end
  end
end

Looking at the source code of Active Record, you can see that you are confirming the type with primary_key_type method.

def primary_key_type
  key_type = options[:primary_key_type]
  ", id: :#{key_type}" if key_type
end

• https://github.com/rails/rails/blob/v5.2.0/activerecord/lib/rails/generators/active_record/migration.rb

If orm’s primary_key_type is default (leave as bigint

class CreateHoges < ActiveRecord::Migration[5.2]
  def change
    create_table :hoges do |t|

      t.timestamps
    end
  end
end

Changed default type of primary_key_type of orm to integer

class CreateFoos < ActiveRecord::Migration[5.2]
  def change
    create_table :foos, id: :integer do |t|

      t.timestamps
    end
  end
end

I think that you can see that id is integer in create_table.

result.

$ mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.7.15 Homebrew

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use modify-rails-activerecord-primary-key_development;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show create table hoges;
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                    |
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| hoges | CREATE TABLE `hoges` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> show create table foos;
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| foos  | CREATE TABLE `foos` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

It can be changed that it is bigint and integer.

Since the contents are released to Github, please confirm if there is an uncertain point.

thank’s :)

teitei-tk/modify-rails-activerecord-primary-key