[英]Setting Unordered List Visibility Asp.net error
I am trying to set the visibility of a "ul" element in c# code behind but getting a null exception 我试图在后面的C#代码中设置“ ul”元素的可见性,但得到空异常
Function behind Page (Master page in this instance) Page(在本例中为母版页)背后的功能
protected void profileDropDown(Object sender, ImageClickEventArgs e)
{
HtmlGenericControl dropDownList = (HtmlGenericControl)Master.FindControl("profileList");
if (dropDownOpen == false)
{
dropDownList.Visible = true;
}
else
{
dropDownList.Visible = false;
}
}
Html behind Page (Master page in this instance) 网页后面的HTML(在这种情况下为母版页)
<body>
<form id="form" runat="server">
<div runat="server" id="navBarContainer">
<img runat="server" id="imgLogo" src="Images/logo_netflix.png"/>
<ul id="navBarLeft">
<li id="liLobbies" class="navItem"><a href="/Lobbies.aspx">Lobbies</a></li>
</ul>
<ul id="navBarRight">
<li id="liProfile" class="navItem">
<div id="profileHeader">
<img id="imgProfilePic" src="Images/img_user.png"/>
<span><asp:Label Text="Profile" runat="server" CssClass="lblProfile"></asp:Label></span>
<asp:ImageButton runat="server" id="imgDropDown" src="Images/icon_down_arrow.png" OnClick="profileDropDown"/>
</div>
<ul id="profileList">
<li id="liAccount" class="navItemProfile"><a class="navItemProfile" href="/Account/Login.aspx">Account</a></li>
<li id="liMessages" class="navItemProfile"><a class="navItemProfile" href="/Account/Login.aspx">Messages</a></li>
</ul>
</li>
<li id="liLogin" class="navItem"><a href="/Account/Login.aspx">Login</a></li>
<li id="liRegister" class="navItem"><a href="/Account/Reigster.aspx">Register</a></li>
</ul>
</div>
<asp:ContentPlaceHolder id="body" runat="server">
</asp:ContentPlaceHolder>
</form>
You must make the ul
runat=server
您必须使
ul
runat=server
<ul id="profileList" runat="server">
<li id="liAccount" class="navItemProfile"><a class="navItemProfile" href="/Account/Login.aspx">Account</a></li>
<li id="liMessages" class="navItemProfile"><a class="navItemProfile" href="/Account/Login.aspx">Messages</a></li>
</ul>
And the you change you method, accessing the element directly 然后您更改方法,直接访问元素
protected void profileDropDown(Object sender, ImageClickEventArgs e)
{
profileList.Visible = !dropDownOpen;
}
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