star-erp/app/Modules/Inventory/Models/InventoryTransaction.php

<?php

namespace App\Modules\Inventory\Models;

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


class InventoryTransaction extends Model
{
    /** @use HasFactory<\Database\Factories\InventoryTransactionFactory> */
    use HasFactory;

    protected $fillable = [
        'inventory_id',
        'type',
        'quantity',
        'unit_cost',
        'balance_before',
        'balance_after',
        'reason',
        'reference_type',
        'reference_id',
        'user_id',
        'actual_time',
    ];

    protected $casts = [
        // actual_time 不做時區轉換，保留原始字串格式（台北時間）
        // 原因：資料庫儲存的是台北時間，但 MySQL 時區為 UTC
        // 若使用 datetime cast，Laravel 會誤當作 UTC 再轉回台北時間，造成偏移
        'unit_cost' => 'decimal:4',
    ];

    public function inventory(): \Illuminate\Database\Eloquent\Relations\BelongsTo
    {
        return $this->belongsTo(Inventory::class);
    }

    public function reference(): \Illuminate\Database\Eloquent\Relations\MorphTo
    {
        return $this->morphTo();
    }
}