Casts property on custom pivot model is not honored for JSON castable attributes

[jrhenderson1988]

#- Laravel Version: 5.4.11

• PHP Version: 7.0.15
• Database Driver & Version: MySQL driver - Maria DB 10.2.3

Description:

When defining a BelongsToMany relationship on an Eloquent model and specifying a custom pivot model with the using method, I am finding that the $casts property on the custom pivot model is not honoured for JSON castable attributes.

Where I have specified a JSON cast on an attribute for the pivot model, I am finding that a string is returned (The JSON itself) when attempting to access that property.

Steps To Reproduce:

Network model

class Network extends Model
{
    public function clients()
    {
        return $this->belongsToMany(Client::class)
            ->using(ClientNetworkPivot::class)
            ->withPivot(['settings']);
    }
}

Client model

class Client extends Model
{
    public function network()
    {
        return $this->belongsToMany(Network::class)
            ->using(ClientNetworkPivot::class)
            ->withPivot(['settings']);
    }
}

Custom pivot model

class ClientNetworkPivot extends Pivot
{
    protected $casts = [
        'settings' => 'array'
    ];
}

Steps

$client = Client::find(1);

$networks = $client->networks;
foreach ($networks as $network) {
    var_dump(get_class($network->pivot), $network->pivot->settings);
}

Expected output

string(36) "App\Models\Pivots\ClientNetworkPivot"
array(0) {
}

Actual output

string(36) "App\Models\Pivots\ClientNetworkPivot"
string(2) "{}"

Additional Information

It seems that in this case, the attribute is being json_encoded again when it's being set in the pivot model. By running var_dump($network->pivot->getAttributes()['settings']); I am getting the following output string(4) ""{}""

#18149

[jrhenderson1988]

I did manage to work out a way to get around this by overriding the Pivot constructor and using the setRawAttributes method in place of the forceFill method. I'm not 100% sure if this may cause any unwanted side effects though.

class ClientNetworkPivot
{
    protected $casts = [
        'settings' => 'array'
    ];

    public function __construct(Model $parent, $attributes, $table, $exists = false)
    {
        $this->setConnection($parent->getConnectionName())
             ->setTable($table)
             ->setRawAttributes($attributes)
             ->syncOriginal();

        $this->parent = $parent;

        $this->exists = $exists;

        $this->timestamps = $this->hasTimestampAttributes();
    }
}

[jrhenderson1988]

This issue has been fixed via #18127 and was released in 5.4.14.