star-erp/app/Models/PurchaseOrderItem.php

<?php

namespace App\Models;

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

class PurchaseOrderItem extends Model
{
    use HasFactory;

    protected $fillable = [
        'purchase_order_id',
        'product_id',
        'quantity',
        'unit_price',
        'subtotal',
        'received_quantity',
    ];

    protected $casts = [
        'quantity' => 'decimal:2',
        'unit_price' => 'decimal:2',
        'subtotal' => 'decimal:2',
        'received_quantity' => 'decimal:2',
    ];

    // 移除 $appends 以避免自動附加導致的錯誤
    // 這些屬性將在 Controller 中需要時手動附加
    // protected $appends = ['productName', 'unit'];

    public function getProductNameAttribute(): string
    {
        return $this->product?->name ?? '';
    }

    public function getUnitAttribute(): string
    {
        // 優先使用採購單位 > 大單位 > 基本單位
        // 與 PurchaseOrderController 的邏輯保持一致
        if (!$this->product) {
            return '';
        }
        
        return $this->product->purchase_unit 
            ?: ($this->product->large_unit ?: $this->product->base_unit);
    }

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

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