IBX-6640: Fixed infinite loop when Normalizer returns an object

[Steveb-p]

Question	Answer
JIRA issue	IBX-6640
Type	bug
Target version	Ibexa v4.5
BC breaks	no
Tests pass	yes
Doc needed	no

When trying to fix an incorrect REST response shape, I have found out that the solution expected cannot work, because it relies on object being returned from Normalizer.
The incorrect response is (note the "data" property):

{
    "ActivityLogList": {
        "_media-type": "application\/vnd.ibexa.api.ActivityLogList+json",
        "_href": "\/api\/ibexa\/v2\/activity_log\/view",
        "ActivityLog": [
            {
                "_media-type": "application\/vnd.ibexa.api.ActivityLog+json",
                "object_id": "test_object_id",
                "object_class": "stdClass",
                "action": "test_action",
                "user_id": 10,
                "logged_at": "__LOGGED_AT__",
                "data": []
            },
            {
                "_media-type": "application\/vnd.ibexa.api.ActivityLog+json",
                "object_id": "test_object_id",
                "object_class": "stdClass",
                "action": "test_action",
                "user_id": 10,
                "logged_at": "__LOGGED_AT__",
                "data": {
                    "foo": "bar"
                }
            }
        ]
    }
}

While the expected output would be:

{
    "ActivityLogList": {
        "_media-type": "application\/vnd.ibexa.api.ActivityLogList+json",
        "_href": "\/api\/ibexa\/v2\/activity_log\/view",
        "ActivityLog": [
            {
                "_media-type": "application\/vnd.ibexa.api.ActivityLog+json",
                "object_id": "test_object_id",
                "object_class": "stdClass",
                "action": "test_action",
                "user_id": 10,
                "logged_at": "__LOGGED_AT__",
                "data": {}
            },
            {
                "_media-type": "application\/vnd.ibexa.api.ActivityLog+json",
                "object_id": "test_object_id",
                "object_class": "stdClass",
                "action": "test_action",
                "user_id": 10,
                "logged_at": "__LOGGED_AT__",
                "data": {
                    "foo": "bar"
                }
            }
        ]
    }
}

To fix this, Ibexa\Rest\Output\Generator\Json\FieldTypeHashGenerator::generateObjectValue() cannot call Ibexa\Rest\Output\Generator\Json\FieldTypeHashGenerator::generateValue(), because this results in an infinite loop.

When looking at Ibexa\Rest\Output\Generator\Json\FieldTypeHashGenerator::generateValue() you can notice that it works on 4 data types:

• null
• scalar
• array
• object

null and scalar work properly, and loop is broken immediately, so we can skip the additional call.

object in current shape becomes an infinite loop. Those two methods keep calling each other.

array has the only special effect among all 4, where it performs a few list related tasks.

See

https://github.com/symfony/symfony/blob/0659364bbc51920ab6475186e40d1bf06a637047/src/Symfony/Component/Serializer/Serializer.php#L166-L173

and

https://github.com/symfony/symfony/blob/0659364bbc51920ab6475186e40d1bf06a637047/src/Symfony/Component/Serializer/Serializer.php#L51-L55

for explanation why objects sometimes are needed after normalization.

TODO:

• Implement tests.
• Fix new code according to Coding Standards ($ composer fix-cs).
• Ask for Code Review.

[sonarqubecloud]

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