[13.x] Fix appended accessors receiving null in toArray()

[lazerg]

When an accessor is defined for an existing attribute and that attribute is also listed in $appends, toArray() returns null for it instead of the accessor's value:

protected $appends = ['price'];

protected function price(): Attribute
{
    return Attribute::get(fn ($price) => $price);
}

$model->price;              // 100
$model->toArray()['price']; // null

The appends loop in attributesToArray() calls mutateAttributeForArray($key, null), so the accessor always receives null no matter what is stored on the model. Reading the same attribute directly goes through getAttributeFromArray(), which is why $model->price and $model->toArray()['price'] disagree.

This passes the raw attribute value into the accessor, the same way direct access already does. Appends that have no backing attribute still receive null, so their behavior is unchanged.

Fixes #60917

[hamdyelbatal122]

Great fix!

One small optimization regarding attributes that may have already been processed/formatted earlier in attributesToArray() (e.g., dates via addDateAttributesToArray or casts via addCastAttributesToArray):

foreach ($this->getArrayableAppends() as $key) {
    $attributes[$key] = $this->mutateAttributeForArray(
        $key, $attributes[$key] ?? $this->getAttributeFromArray($key)
    );
}

Using $attributes[$key] ?? $this->getAttributeFromArray($key) reuses any value already populated in $attributes before falling back to reading the raw attribute from the model.

[hamdyelbatal122]

Refined attribute array mutation inline suggestion

[hamdyelbatal122]

Suggested change

	$attributes[$key] = $this->mutateAttributeForArray($key, $this->getAttributeFromArray($key));
	$attributes[$key] = $this->mutateAttributeForArray(
	$key, $attributes[$key] ?? $this->getAttributeFromArray($key)
	);

[lazerg]

Thanks for looking at this, but I don't think this is safe. mutateAttributeForArray always expects the raw, pre-mutation value, that's exactly how addMutatedAttributesToArray calls it a few lines earlier for the normal attributes.

If the append key also has an accessor mutator, addMutatedAttributesToArray already ran the accessor on it and stored the mutated output in $attributes[$key] before we get to the appends loop. Using $attributes[$key] here would feed that already-mutated value back into mutateAttributeForArray, so the accessor runs twice: once on the raw value, once on its own output.

getAttributeFromArray gives the raw stored value, the same thing a normal (non-appended) access to that attribute passes into its mutator. That's what keeps accessors getting what they expect.

[hamdyelbatal122]

Ah, that makes complete sense! Excellent point regarding avoiding double-mutation when addMutatedAttributesToArray has already processed the attribute into $attributes[$key].

Passing the raw value via $this->getAttributeFromArray($key) indeed guarantees that the accessor receives the pristine stored value, exactly matching direct property access.

Appreciate the detailed explanation! Looks solid.