'json', 'aliquota_iva' => 'decimal:2', 'imponibile' => 'decimal:2', 'imposta' => 'decimal:2', 'prezzo_unitario' => 'decimal:2', 'quantita' => 'decimal:2', ]; public function causal() { return $this->belongsTo(Causal::class); } public function receipt() { return $this->belongsTo(Receipt::class, 'receip_id', 'id'); } public function course() { return $this->belongsTo(Course::class); } public function subscription() { return $this->belongsTo(Subscription::class, 'subscription_id'); } }