InvoiceShelf/app/Models/PaymentAllocation.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;

class PaymentAllocation extends Model
{
    use HasFactory;

    protected $guarded = ['id'];

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

    public function payment(): BelongsTo
    {
        return $this->belongsTo(Payment::class);
    }

    public function invoice(): BelongsTo
    {
        return $this->belongsTo(Invoice::class);
    }
}