问题描述

我有一个包含 asp:Literal 的用户控件.

<asp:Literal id="MenuContainer" runat="server"/></div>

代码隐藏页面中有一个初始化控件的方法:

internal void Setup(MyBusinessObject obj){MenuObject menu = MenuHelper.GetMenu(obj.State);如果(obj == null)MenuContainer.Visible = false;//其他代码}

在使用控件的页面中，我在 LoadComplete 事件处理程序中调用 Setup 控制方法(我首先在 Load 中调用它事件).无论 MyBusinessObject 是 null 还是非 null，当我在用户控件上访问 Literal 时，我都会收到错误:

对象引用未设置为对象的实例.

这是什么原因，有什么补救措施?

很简单.正如 Rick Sthral 在他的一篇文章中所建议的那样，我在 web.config 的控制部分添加了一些东西( :( 了解帖子，你必须在他的页面上搜索).

很好地允许我在不放置 @Register 标记的情况下添加控件，但缺点是我的控件上的子控件显示为空！所以我只是将 @Register 指令放在我的页面中，它就起作用了.

I've a user control which contains asp:Literal.

<div>
     <asp:Literal id="MenuContainer" runat="server" />
</div>

There is a method in code-behind page which initializes the control:

internal void Setup(MyBusinessObject obj)
{
    MenuObject menu = MenuHelper.GetMenu(obj.State);

    if(obj == null)
        MenuContainer.Visible = false;

    //other code
}

In the page where the control is used I call Setup method of control in LoadComplete event handler (I was first calling it in Load event). Irrespective of MyBusinessObject being null or not null, when I access Literal on user-control I get error:

Object reference not set to an instance of an object.

What is the reason and what is the remedy for this?

It was very simple. I was adding things in web.config's controls section as was suggested by Rick Sthral in one of his post ( :( for got about the post, you will have to search on his page).

It was nicely allowing me to add controls without putting @ Register tag but the downside was that child controls on my controls were shown as null! so I simply put @ Register directive in my pages and it worked.

这篇关于asp:用户控件中的文字控件 null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！