Doctrine ORM 2: readonly entity properties fail with the legacy proxies #166

Description

composer.json allows doctrine/orm ^2.20 || ^3.5, but the entities have readonly properties since v3.2: ProcessExecution::$code, $startDate, $logFilename, and LogRecord::$channel, $level, $message, $context, $createdAt, $processExecution.

With Doctrine ORM 2 and its legacy proxies (doctrine/common proxy generator, i.e. DoctrineBundle 2 without doctrine.orm.enable_lazy_ghost_objects: true), creating a proxy of these entities fails, e.g. when a LogRecord is loaded with its processExecution relation:

Cannot unset readonly property CleverAge\UiProcessBundle\Entity\ProcessExecution::$code
from scope Proxies\__CG__\CleverAge\UiProcessBundle\Entity\ProcessExecution

Found by the lowest dependencies CI job of #164 (PR #165): requiring the PHP polyfills made --prefer-lowest resolve doctrine/orm 2.20.0 instead of 3.6.0, and 2 tests of LogRecordCrudTest failed. The test kernel now enables the lazy ghost objects on ORM 2 (tests/App/TestKernel.php, as the DoctrineBundle 2 Symfony recipe does), but an application on ORM 2 without this setting gets the error (log records list, execution details...).

Proposed fix

Two options, to decide:

1. Keep ORM 2 support: document the requirement (doctrine.orm.enable_lazy_ghost_objects: true with ORM 2, set by the Symfony recipe of DoctrineBundle 2.x) in the installation documentation, and fail early with an explicit message, e.g. a check when the container is compiled (ORM 2 detected and lazy ghost objects disabled), instead of the PHP error at runtime.
2. Drop ORM 2: require doctrine/orm ^3.5 (ORM 2 only gets security fixes), remove the test kernel workaround and simplify the CI matrix. This is a dependency change: applications still on ORM 2 must stay on ui-process-bundle 3.2 or upgrade Doctrine.

Requirements

• Documentation updates
  • Reference
  • Changelog
• Unit tests

Breaking changes

Option 1: none. Option 2: applications on Doctrine ORM 2 can no longer install the next version (to be released in a minor version only if considered acceptable, since ORM 2 setups without lazy ghost objects are already broken since v3.2; otherwise in the next major).