Activerecord: Insert fails on composed_primary_key model with id as not null Identity column

[rafaelsouza]

Steps to reproduce

With default of 7x config.active_record.partial_inserts = false inserts are failing on a composite primary key with id as IDENTITY column. I can get a workaround by reverting config.active_record.partial_inserts to true.

I also experimented a possible solution on main...rafaelsouza:rails:rafaelsouza/fix-composed-primary-key-bug-with-identity-generated-id . I know it can be solved a couple of different ways, if this is reasonable let me know.

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  gem "activerecord", "~> 7.1"
  gem "pg", "~> 1.5.4"
end

require "active_record"
require "minitest/autorun"
require "logger"

ActiveRecord::Base.partial_inserts = false

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "postgresql", host: "localhost", database: "rails")
ActiveRecord::Base.logger = Logger.new(STDOUT)
ActiveRecord::Base.connection.exec_query("drop table if exists companies");
ActiveRecord::Base.connection.exec_query(<<~SQL)
  create table companies (
    id integer NOT NULL GENERATED BY DEFAULT AS IDENTITY ( INCREMENT 1 START 1 MINVALUE 1 MAXVALUE 2147483647 CACHE 1 ),
    CONSTRAINT companies_pkey PRIMARY KEY (id)
  );
SQL

ActiveRecord::Base.connection.exec_query("drop table if exists users");
ActiveRecord::Base.connection.exec_query(<<~SQL)
  create table users (
    company_id integer NOT NULL,
    id integer NOT NULL GENERATED BY DEFAULT AS IDENTITY ( INCREMENT 1 START 1 MINVALUE 1 MAXVALUE 2147483647 CACHE 1 ),
    name text,
    CONSTRAINT users_pkey PRIMARY KEY (company_id, id)
  );
SQL

class Company < ActiveRecord::Base
  has_many :users
end

class User < ActiveRecord::Base
  self.primary_key = [:company_id, :id]
  belongs_to :company
end

class BugTest < Minitest::Test
  def test_error
    company = Company.create!
    company.users.create!(name: "John")

    assert_equal 1, company.users.count
  end
end

Expected behavior

Actual behavior

ActiveRecord::NotNullViolation: PG::NotNullViolation: ERROR: null value in column "id" of relation "users" violates not-null constraint

System configuration

Rails version: 7.1.x

Ruby version: 3.3