Nullable DateTime? 格式轉換問題 tostring()

解決方案：

DateTime? dt2 = DateTime.Now;
dt2.GetValueOrDefault().ToString("yyyy-MM-dd");

控制器代碼：

public ViewResult index()
{
    var db = new db_context();
    var model = db.test;
    return View(model);
}

views代碼：

<table border="1" cellpadding="6" cellspacing="0" bordercolor="#CCC" style="border-collapse:collapse;">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.test_title)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.create_time)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.update_time)
        </th>
        <th></th>
    </tr>
    @foreach (var item in Model)
    {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.test_title)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.create_time)
            </td>
            <td>
                @item.update_time.GetValueOrDefault().ToString("yyyy-MM-dd HH:mm")
            </td>
            <td>
                @Html.ActionLink("Edit", "Edit", new { id = item.id }) |
                @Html.ActionLink("Details", "Details", new { id = item.id }) |
                @Html.ActionLink("Delete", "Delete", new { id = item.id })
            </td>
        </tr>
    }
</table>

頁面效果：