Defines the primary key field. Use of the native PostgreSQL UUID type is supported, and can be used by defining your tables as such:
create_table :stuffs, id: :uuid do |t|
t.string :content
t.timestamps
end
By default, this will use the +gen_random_uuid()+ function from the pgcrypto
extension. As that extension is only available in PostgreSQL 9.4+, for earlier versions an explicit default can be set to use +uuid_generate_v4()+ from the uuid-ossp
extension instead:
create_table :stuffs, id: false do |t|
t.primary_key :id, :uuid, default: "uuid_generate_v4()"
t.uuid :foo_id
t.timestamps
end
To enable the appropriate extension, which is a requirement, use the enable_extension
method in your migrations.
To use a UUID primary key without any of the extensions, set the :default
option to nil
:
create_table :stuffs, id: false do |t|
t.primary_key :id, :uuid, default: nil
t.uuid :foo_id
t.timestamps
end
You may also pass a custom stored procedure that returns a UUID or use a different UUID generation function from another library.
Note that setting the UUID primary key default value to nil
will require you to assure that you always provide a UUID value before saving a record (as primary keys cannot be nil
). This might be done via the SecureRandom.uuid
method and a before_save
callback, for instance.
Calls superclass method
# File activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb, line 44
def primary_key(name, type = :primary_key, **options)
options[:auto_increment] = true if [:integer, :bigint].include?(type) && !options.key?(:default)
if type == :uuid
options[:default] = options.fetch(:default, "gen_random_uuid()")
elsif options.delete(:auto_increment) == true && %(integer bigint).include?(type)
type = if type == :bigint || options[:limit] == 8
:bigserial
else
:serial
end
end
super
end