#primary_key(name, type = :primary_key, **options)
Defines the primary key field. Use of the native ::ActiveRecord::ConnectionAdapters::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.
end
By default, this will use the gen_random_uuid()
function from the pgcrypto
extension. As that extension is only available in ::ActiveRecord::ConnectionAdapters::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.
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.
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.
# File 'activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb', line 48
def primary_key(name, type = :primary_key, ** ) if type == :uuid [:default] = .fetch(:default, "gen_random_uuid()") end super end