Update on single-attribute models is not supported

[tagliala]

This rarely presents a problem. However, if you're writing a reduced test case, keep in mind that the minimum supported number of attributes in a table is 2

How to replicate:

# migration
create_table :countries, temporal: true do |t|
  t.string :name
end

# model
class Country < ApplicationRecord
  include ChronoModel::TimeMachine

  validates :name, presence: true
end

> Country.create name: 'Italy'
  TRANSACTION (0.1ms)  BEGIN
  Country Create (5.4ms)  INSERT INTO "countries" ("name") VALUES ($1) RETURNING "id"  [["name", "Italy"]]
  TRANSACTION (0.2ms)  COMMIT

> Country.last.update name: 'Italia'
  Country Load (0.9ms)  SELECT "countries".* FROM "countries" ORDER BY "countries"."id" DESC LIMIT $1  [["LIMIT", 1]]
  TRANSACTION (0.1ms)  BEGIN
  Country Update (4.4ms)  UPDATE "countries" SET "name" = $1 WHERE "countries"."id" = $2  [["name", "Italia"], ["id", 1]]
  TRANSACTION (0.1ms)  ROLLBACK
~/.rvm/gems/ruby-3.1.2/gems/activerecord-7.0.4/lib/active_record/connection_adapters/postgresql_adapter.rb:768:in `exec_params': PG::FeatureNotSupported: ERROR:  source for a multiple-column UPDATE item must be a sub-SELECT or ROW() expression (ActiveRecord::StatementInvalid)
LINE 1: UPDATE ONLY temporal.countries SET ( "name" ) = ( NEW."name"...
                                                          ^
QUERY:  UPDATE ONLY temporal.countries SET ( "name" ) = ( NEW."name" ) WHERE id = OLD.id
CONTEXT:  PL/pgSQL function chronomodel_countries_update() line 34 at SQL statement
~/.rvm/gems/ruby-3.1.2/gems/activerecord-7.0.4/lib/active_record/connection_adapters/postgresql_adapter.rb:768:in `exec_params': ERROR:  source for a multiple-column UPDATE item must be a sub-SELECT or ROW() expression (PG::FeatureNotSupported)
LINE 1: UPDATE ONLY temporal.countries SET ( "name" ) = ( NEW."name"...
                                                          ^
QUERY:  UPDATE ONLY temporal.countries SET ( "name" ) = ( NEW."name" ) WHERE id = OLD.id
CONTEXT:  PL/pgSQL function chronomodel_countries_update() line 34 at SQL statement

Workarounds

• Add timestamps
• Add another field