finance_app/app/Models/InvestmentTransaction.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class InvestmentTransaction extends Model
{
    protected $fillable = [
        'holding_id',
        'action',
        'shares',
        'price',
        'fee',
        'tax',
        'traded_at',
        'note',
        'amount', // 實際投入金額（基金用）
        'nav',    // 淨值（基金用）
    ];

    protected $casts = [
        'traded_at' => 'date',
    ];

    public function holding()
    {
        return $this->belongsTo(InvestmentHolding::class, 'holding_id');
    }
}