Demonstration of PostLoad events not being triggered when retrieving objects by reference

Usage

This application requires an executable file bin/php that loads the correct PHP binary (as generated by our internal tool phlough on phlough install).

First, install dependencies and create a new database with the correct schema (will create an SQLite database in ./tmp)

composer install

bin/doctrine orm:schema-tool:create

Create an Entity and load it normally

bin/create-new-entity # assume it creates an entity with id 1
bin/load-entity 1 # Output should contain: PostLoad EventListener called for Entity\Test#1

Load the same entity by reference and access a property to trigger initialisation

bin/load-entity-by-reference-and-access-proprty 1 # Will the output contain: "PostLoad EventListener called"?

This repository is there to change the implementation around (upgrade/downgrade Doctrine versions, change the configuration in EntityManagerFactory, use different kinds of properties in the Test entity) and test how initialisation/PostLoad event behaviour changes.

Explanation

When loading an entity by reference, whether the object will be initialised on a method call or property access depends on the implementation of uninitialised object. Using either doctrine/orm 2.x or 3.x, there are 3 possible implementations:

Proxy using Doctrines Proxy Generator (doctrine 2.x default, gone in doctrine 3.x)

Proxies will be initialised on method calls.

See doctrine/DoctrineBundle#1651 (comment)

"Lazy Ghost Object" using Symfony's VarExporter\LazyGhostTrait (doctrine 3.x default)

Proxies will be initialised only when accessing mapped properties. This could become a problem if you want to initialise an unmapped property via the PostLoad event.

See doctrine/DoctrineBundle#1651 (comment)

However, using this repository, we found out that this is not true for unmapped properties inside Embeddables: Access to unmapped properties inside Embeddables will trigger initialisation (unlike unmapped properties directly on the Entity).

PHP 8.4 Native lazy objects (requires PHP 8.4+ and doctrine/orm 3.x and `$config->enableNativeLazyObjects(true);`)

Could not test as we have no PHP 8.4 environment yet.

https://www.php.net/manual/en/language.oop5.lazy-objects.php#language.oop5.lazy-objects.initialization-triggers implies that access to all properties (mapped and unmapped) will trigger initialisation.