InvoiceShelf/app/Domains/Receivables/Models/PaymentAllocation.php

<?php

namespace App\Domains\Receivables\Models;

use App\Domains\Sales\Models\Invoice;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;

class PaymentAllocation extends Model
{
    protected $table = 'payment_allocations';

    use HasFactory;

    protected $guarded = ['id'];

    protected function casts(): array
    {
        return [
            'amount' => 'integer',
            'base_amount' => 'integer',
        ];
    }

    /**
     * The receipt this slice was taken out of.
     */
    public function payment(): BelongsTo
    {
        return $this->belongsTo(Payment::class, 'payment_id');
    }

    /**
     * The document this slice was booked against.
     */
    public function invoice(): BelongsTo
    {
        return $this->belongsTo(Invoice::class, 'invoice_id');
    }
}