[5.6] withTimestamps() never applied to custom pivot model

[stayallive]

• Laravel Version: 5.6.12
• PHP Version: 7.2.0
• Database Driver & Version: MySQL 5.7.20

Description:

When calling ->withTimestamps() on a belongs to many relation it is never applied to a custom pivot model registered with ->using().

Steps To Reproduce:

Create a model for example Domains that belongs to many to Certificates using the following relation method:

use Illuminate\Database\Eloquent\Model;

class Domain extends Model 
{
    public function certificates()
    {
        return $this->belongsToMany(Certificate::class)
                    ->using(CertificateDomain::class)
                    ->withTimestamps();
    }
}

The pivot model was reduced to the bare minimum to rule out a user error:

use Illuminate\Database\Eloquent\Relations\Pivot;

class CertificateDomain extends Pivot
{
}

Observe that when updating the pivot model via the updated_at will not be updated:

$certificate = Domain::find(1)->certificates()->first();
$certificate->pivot->some_column = 'something';
$certificate->pivot->save();

When confirming the timestamps attribute on the model is true we see it's not:

$certificate = Domain::find(1)->certificates()->first();
dd($certificate->pivot->timestamps); // false

When defining the relationship like this:

use Illuminate\Database\Eloquent\Model;

class Domain extends Model 
{
    public function certificates()
    {
        return $this->belongsToMany(Certificate::class)
                    //->using(CertificateDomain::class)
                    ->withTimestamps();
    }
}

The updated_at column will be updated when the pivot model is saved.

[cetetesoft]

I've had the same issue. Apparently the custom pivot is created using Pivot::fromAttributes() with an empty array as $attributes, so $instance->timestamps is always set to false.

[luchaos]

It took me ages to find out but came to the same conclusion (before finding this issue):
a738129#r28662738
Thanks for showing me the ->using(CertificateDomain::class) line btw @stayallive - i can finally remove all those verbose newPivot() overrides within my custom pivot classes. Just found out that's in the docs since 5.4; the more you know...