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