List<SelectListItem> items = new List<SelectListItem>();
if (a)
{
    SelectListItem deliveryItem = new SelectListItem()
    {
        Selected = a.selected,Text = "Delivery",Value = "1"
    };
 
    items.Add(deliveryItem);
}
 
if (b)
{
    SelectListItem pickupItem = new SelectListItem()
    {
        Selected = b.selected,Text = "Pickup",Value = "2"
    };
 
    items.Add(pickupItem);
}
 
SelectList selectList = new SelectList(items);
 
ViewData["OrderTypeList"] = selectList;

然后使用它

Html.DropDownList("OrderTypeList")

呈现

<select id="OrderTypeList" name="OrderTypeList"><option>System.Web.Mvc.SelectListItem</option>
<option>System.Web.Mvc.SelectListItem</option>
</select>

为什么它没有正确渲染选项？