'int', 'subscription_id' => 'int', ]; protected $fillable = [ 'invoice_id', 'insurance_id', 'subscription_id', 'amount', 'payment_deadline', 'payment_reminder', 'state', 'reason' ]; public function insurance() { return $this->belongsTo(NhInsurance::class, 'insurance_id'); } public function subscription() { return $this->belongsTo(NhInsurancesSubscription::class, 'subscription_id'); } }