neptunesoftware / laravel-invoice

src/Traits/IsInvoiceable.php

<?php

namespace NeptuneSoftware\Invoice\Traits;

use NeptuneSoftware\Invoice\Models\InvoiceLine;

trait IsInvoiceable
{
    /**
     * Set the polymorphic relation.
     *
     * @return mixed
     */
    public function invoiceLines()
    {
        return $this->morphMany(InvoiceLine::class, 'invoiceable');

It seems like morphMany() must be provided by classes using this trait. How about adding it as abstract method to this trait?

    }
}