每当我尝试从我自己的 PayPal 表单中订购商品时，所有值都必须大于 0。我怎样才能让它只订购一件商品而另一件商品设置为零
错误消息：您输入了无效的数量值。数量值必须是大于或等于一的整数。
示例代码：JSFiddle
<form action="https://www.paypal.com/cgi-bin/webscr" method="post" target="_blank">
<input name="cmd" type="hidden" value="_cart" />
<input type="hidden" name="upload" value="1" />
<input name="currency_code" type="hidden" value="USD" />
<input name="business" type="hidden" value="test@example.com" />
Italian on Wheat Bread
<input type="hidden" name="amount_1" value="6.00" />
<input type="hidden" name="item_name_1" value="Italian on Wheat Bread" />
<input type="number" name="quantity_1" value="0" />
<br />
Turkey on White Bread
<input type="hidden" name="amount_2" value="6.00" />
<input type="hidden" name="item_name_2" value="Turkey on White Bread" />
<input type="number" name="quantity_2" value="0" />
<br />
Vegetarian on Wheat Bread
<input type="hidden" name="amount_3" value="6.00" />
<input type="hidden" name="item_name_3" value="Vegetarian on Wheat Bread" />
<input type="number" name="quantity_3" value="1" />
<br />
<input type=submit />
</form>