获取一个DropDownList来检查asp.net/C#一个复选框 [英] Getting a dropdownlist to check a checkbox in asp.net/C#

问题描述

<input runat ="server" type ="checkbox" id="helprequest" />     
<label for="helprequest">Help request</label>
<asp:DropDownList ID="options" runat="server" OnSelectedIndexChanged="checkHelpRequest">
    <asp:ListItem Text="Windows"></asp:ListItem>
    <asp:ListItem Text="Macintosh"></asp:ListItem>
    <asp:ListItem Text="Linux"></asp:ListItem>
    <asp:ListItem Text="Other"></asp:ListItem>
</asp:DropDownList>

在我的codebehind，我有

In my codebehind, I have

protected void checkHelpRequest(object sender, EventArgs e)
{
    helprequest.Checked = true;
}

但是，当我选择DropDownList的东西，复选框，没有得到作为托运标记，我怎么当我改变一个DropDownList指数的​​复选框以显示为检查？

But when I select something on the dropdownlist, the checkbox, does not get marked as checked, how do I get the checkbox to appear as checked when I change the index on a dropdownlist?

推荐答案

您的DropDownList 没有的AutoPostBack ='真正的'设置。如果不设置此，您的下拉列表将不会回来后，当您更改选定的索引。

Your DropDownList does not have AutoPostBack='true' set. Without setting this, your dropdown will not post back when you change the selected index.

只是将其更改为：

<asp:DropDownList AutoPostBack="true" ID="options" 
      runat="server" OnSelectedIndexChanged="checkHelpRequest">

如果不设置这个，你的 checkHel prequest 方法会继续当你的下拉变化指数，但回发的部分只造成之后调用其他控制，就像一个按钮，或者其他的DropDownList的确实的具有的AutoPostBack集。

Without setting this, your checkHelpRequest method will still be called when your drop down changes index, but only after a postback is caused by some other control, like a button, or another DropDownList that does have AutoPostBack set.

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