使用!=比较GridView新旧值出现意外结果的原因咨询

AI 小北

2026-6-21

问题原因及解决方法

核心原因

你用e.NewValues["Schedule"] != e.OldValues["Schedule"]做比较时，本质是引用类型的相等性检查——因为NewValues和OldValues存储的是装箱后的object实例，哪怕两个实例的DateTime值完全相同，只要是不同的对象实例，引用比较就会返回true。

解决步骤

把两个值先转换为DateTime类型，再做值比较：

修改后的代码示例

private bool UpdateWaiveItemShortShipCheckingPass(GridViewUpdateEventArgs e)
{
    DateTime TargetReplenishmentSchedule;

    if (!DateTime.TryParse(TextBoxTargetReplenishmentSchedule.Text.Trim(), out TargetReplenishmentSchedule))
    {
        ShowJavaScriptMessage("TextBoxTargetReplenishmentScheduleIsNotDate", "Target Replenishment Schedule is not a date!");
        return false;
    }

    var oldScheduleObj = e.OldValues["Schedule"];
    var newScheduleObj = e.NewValues["Schedule"];

    if (oldScheduleObj != null && newScheduleObj != null)
    {
        // 转换为DateTime类型后做值比较
        var oldSchedule = (DateTime)oldScheduleObj;
        var newSchedule = (DateTime)newScheduleObj;

        if (oldSchedule != newSchedule)
        {
            if (TargetReplenishmentSchedule.Date < DateTime.Now.Date)
            {
                ShowJavaScriptMessage("invalidTargetReplenishmentSchedule", "Target Replenishment Schedule must be on or after today!");
                return false;
            }
        }
    }
    return true;
}