class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::TableDefinition

def column(name, type = nil, options = {})
  super
  column = self[name]
  column.array = options[:array]
  self
end

def create_column_definition(name, type)
  ColumnDefinition.new name, type
end

for instance.
done via the SecureRandom.uuid method and a +before_save+ callback,
before saving a record (as primary keys cannot be nil). This might be
will require you to assure that you always provide a UUID value
Note that setting the UUID primary key default value to +nil+

or another library.
You may also pass a different UUID generation function from +uuid-ossp+

end
t.timestamps
t.uuid :foo_id
t.primary_key :id, :uuid, default: nil
create_table :stuffs, id: false do |t|

set the +:default+ option to nil:
migrations To use a UUID primary key without +uuid-ossp+ enabled, you can
the +uuid-ossp+ extension, you can use the +enable_extension+ method in your
+uuid-ossp+ extension, which MUST be enabled on your databse. To enable
By default, this will use the +uuid_generate_v4()+ function from the

end
t.timestamps
t.string :content
create_table :stuffs, id: :uuid do |t|

by defining your tables as such:
Use of the native PostgreSQL UUID type is supported, and can be used
Defines the primary key field.

def primary_key(name, type = :primary_key, options = {})
  return super unless type == :uuid
  options[:default] = options.fetch(:default, 'uuid_generate_v4()')
  options[:primary_key] = true
  column name, type, options
end