How to use long id in Rails applications?

Question

How can I change the (default) type for ActiveRecord\'s IDs? int is not long enough, I would prefer long. I was surprised that there is no :long for the migrations - does on

Answer 1

To set the default primary key column type, the migration files are not the place to mess with.

Instead, just stick this at the bottom of your config/environment.rb

ActiveRecord::ConnectionAdapters::MysqlAdapter::NATIVE_DATABASE_TYPES[:primary_key] = "BIGINT UNSIGNED DEFAULT NULL auto_increment PRIMARY KEY"

And all your tables should be created with the intended column type for id:

+--------------+---------------------+------+-----+---------+----------------+
| Field        | Type                | Null | Key | Default | Extra          |
+--------------+---------------------+------+-----+---------+----------------+
| id           | bigint(20) unsigned | NO   | PRI | NULL    | auto_increment | 

After you've done what you've set out to do... the next question is probably "How do I make my foreign key columns the same column type?" since it does not make sense to have primary key people.id as bigint(20) unsigned, and person_id be int(11) or anything else?

For those columns, you can refer to the other suggestions, e.g.

t.column :author_id, 'BIGINT UNSIGNED'
t.integer :author_id, :limit => 8

UPDATE: @Notinlist, to use arbitrary column for primary key on arbitrary tables you need to do the create_table-change_column dance:

create_table(:users) do |t|
  # column definitions here..
end
change_column :users, :id, :float # or some other column type

e.g. if I wanted guid instead of auto-increment integers,

create_table(:users, :primary_key => 'guid') do |t|
  # column definitions here..
end
change_column :users, :guid, :string, :limit => 36

Answer 2

According to the Rails API documentation, the possible options for type are:

:string
:text
:integer
:float
:decimal
:datetime
:timestamp
:time
:date
:binary
:boolean

You can use :decimal, or you can execute a command directly if you need to:

class MyMigration
  def self.up
    execute "ALTER TABLE my_table ADD id LONG"
  end
end

As wappos pointed out, you can use auxiliary options like :limit to tell ActiveRecord how large you want the column to be. So you would use the :int column with a larger :limit.

Answer 3

You can do it like this:

class CreateUsers < ActiveRecord::Migration[5.0]
  def change
    create_table :users, id: :bigserial do |t|
      t.string :name
    end
  end
end

Answer 4

In rails4, you can do it.

Following is an example to create a Dummy model in rails4 & postgres,

xxx_migrate_dummies.rb:

class CreateDummies < ActiveRecord::Migration
  def change
    create_table :dummies, :id => false do |t|
      t.column :id, :serial8, primary_key: true
      t.string :name, :limit => 50, null: false
      t.integer :size, null: false

      t.column :create_date, :timestamptz, null: false
    end
  end
end

What it did:

• It use serial8 as id type, which is 64 bit integer, and define it as primary key.
• It use timestamptz as datetime type, which contain the timezone info, this is important for a application that go across multiple timezones.

Answer 5

Rails 3, MySQL:

t.column :foobar, :int, :limit => 8

Does not give me a bigint, only an int. However,

t.column :twitter_id, 'bigint'

works fine. (Although it does tie me to MySQL.)