Relationships validation fails when sending an empty object

[veneliniliev]

When sending an empty relationships object ({}), the API responds with an error saying "The member relationships must be an object."

According to the JSON:API specification, this should be valid — an empty object for relationships is allowed when there are simply no relationships to define.

The issue appears to originate from the following check in RelationshipsValidator.php:

if (!is_object($relationships)) {
    return $errors->push(
        $this->translator->memberNotObject('/data', 'relationships')
    );
}

Even though {} is an object in JSON, by the time the validation runs, $relationships may already have been converted to an array, triggering this error.

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✅ Expected Behavior

The validator should accept an empty object {} as a valid relationships value and not return an error.

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🛠 Suggested Fix

Ensure that $relationships remains an object or adjust the validation logic to correctly handle empty objects.
For example, confirm the type before validation or modify the check to allow empty arrays/objects when appropriate.

if (!is_object($relationships) && !empty($relationships)) {
    // only push error if it's not an object AND not empty
    return $errors->push(
        $this->translator->memberNotObject('/data', 'relationships')
    );
}

Request example:

{
    "data": {
        "type": "xxxx",
        "id": "5",
        "attributes": {
            "deleted_at": null
        },
        "relationships": {}
    }
}

Response:

{
    "jsonapi": {
        "version": "1.0"
    },
    "errors": [
        {
            "detail": "The member relationships must be an object.",
            "source": {
                "pointer": "/data/relationships"
            },
            "status": "400",
            "title": "Non-Compliant JSON:API Document"
        }
    ]
}

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