[12.x] Fixes incorrectly serializing virtual properties

[DarkGhostHunter]

The problem

When adding virtual properties to models, serializing them (like when happens when these are stored in a cache store) will return an error.

For example, consider the following model:

class Cart extends Model
{

    public $total {
        get => $this->items->sumBy('net') * $this->items->sumBy('amount');
        set {
            $count = $this->items->sumBy('amount');

            $this->items->each(fn ($item) => $item->net = $value / $count);
        }
    }

    // ..
}

When trying to serialize it with serialize($model), like it happens when using the application cache, it will return an error like this:

serialize(): "total" returned as member variable from __sleep() but does not exist

This may be cumbersome if someone is adding virtual properties to a model for whatever reason, like live calculation or else, because the patchwork is to alter the __sleep() method on each offending class, or use alternative abstract Model and hope nothing breaks in between.

The Fix

The fix uses a simple (array) cast to the model instance to get the non-virtual keys, and an array_map to clean the name of each key returned.

[taylorotwell]

Can this have a test?

[DarkGhostHunter]

There. I fixed it. Took some magic because it's PHP 8.4 code running on previous versions, so I had to add a reusable rule to the styleci.yml and use eval so PHP didn't pick up the code that wasn't able to understand.

[taylorotwell]

Is there a way to do this without the array cast?

[dkulyk]

    public function __serialize(): array
    {
        $this->mergeAttributesFromCachedCasts();

        $props = get_mangled_object_vars($this);

        // Remove the attributes that are should be unserialized with default values
        unset(
            $props["\0*\0classCastCache"],
            $props["\0*\0attributeCastCache"],
            $props["\0*\0relationAutoloadCallback"],
            $props["\0*\0relationAutoloadContext"],
        );

        return $props;
    }

It is only suggestion.

1. __serialize will make the same serialized output like __sleep except compared to the current implementation - get_mangled_object_vars will returns all private props for all inherited classes, which is more correct behavior

2. We no need reset any caches, only remove them from serialized data.

get_mangled_object_vars($obj) is equivalent of (array)$obj and ignores virtual and unitialized props.

[DarkGhostHunter]

Using get_mangled_object_vars() still doesn't save you from cleaning the property names, and from what I know, is slower than just (array) $this while giving the exact same results.

I modified the PR with your suggestion for removing the cache keys from the props instead of the instance.

Another alternative is to use ReflectionObject but not a fan of that since it adds some overhead that you may skip if you set another cache in the class, and even then it wouldn't be a solution if a developer sets dynamic properties into the model.

[dkulyk]

still doesn't save you from cleaning the property names

You no need to clean them if you will use __serialize instead __sleep as in the example

[DarkGhostHunter]

Dunno if I can just use serialize. Theoretically it will be just fine, so I’ll update that then. I hope there is no dev using a custom serialization.Once it’s accepted I’m gonna back port it to 11.x. 

[DarkGhostHunter]

Can someone te run this again. Seems that docker failed.

[taylorotwell]

May revisit this for Laravel 13.x. Will note it on my todo list.