SerializationGraphNavigator unaware of serializeNull change of context when altered in PreSerializeEvent

[gabrielspiteri-highlight]

Q	A
Bug report?	yes
Feature request?	no
BC Break report?	yes
RFC?	no

SerializationGraphNavigator doesn't take into account a possible change in the serializeNull property of the context when altered in a PreSerializeEvent.

Steps required to reproduce the problem

1. Configure JMS to serialize_null: false
2. Start serializing an object that has a null value property
3. Add a pre serialize event subscriber
4. In the event call $event->getContext()->setSerializeNull(true)

Expected Result

• The object's properties with a null value should be included in the resulting JSON

Actual Result

• The object's properties with a null value are not included.

[goetas]

::setSerializeNull(true) should not be called inside event listeners... actually should trigger an exception if done so. So most likely it is a bug.

When the serialization is started, the context should be in read-only mode.
See

serializer/src/Context.php

Line 133 in 5286388

private function assertMutable(): void

, assertMutable should be called inside setSerializeNull

[goetas]

See #1159

[gabrielspiteri-highlight]

Alright is there a better way to configure specific entities only to serialize nulls ?

[goetas]

hmm, not really... serialize null is defined in the context, there is no easy way to do it per-entity

[gabrielspiteri-highlight]

@goetas Well changing it in the PreSerializeEvent was pretty easy :) ... However I think we could handle it if the Navigators shouldSerializeNull property had a setter function ? ... Currently we worked around the limitation by calling the initialize function with an altered context object than in PostSerialize we set it back to its original value