HtmlGenericControl列表始终返回null

Question

我有一个函数可以加载联系人列表，并在每个联系人旁边放置一个复选框。任何被勾选的联系人都会收到一封电子邮件。但在我的电子邮件函数中，列表总是返回为零。

列表代码：

   <div id="viewMenuDropFollowup" style="top:0px;right:10px; text-align: left; display:none">
                    <strong>Email to</strong> <a onclick="OpenEmail()" style="float:right;font-weight:bold;cursor:pointer">X</a>
                    <ul runat="server" id="ulCRMContacts">

                    </ul>
                    <asp:TextBox runat="server" ID="txtEmailTo" ></asp:TextBox>
                    <asp:LinkButton runat="server" ID="btnEmail3" CssClass="btnEmail" OnClick="btnEmail_Click" Text="Email" ToolTip="Email to selected contacts" OnClientClick="return CheckEmail()"></asp:LinkButton>
                </div>
                <a id="btnOpenEmail" onclick="OpenEmail()" class="EmailClass"><strong>Email</strong></a>

function OpenEmail() {
        if (document.getElementById("viewMenuDropFollowup").style.display === "block") {
            document.getElementById("viewMenuDropFollowup").style.display = "none";
        } else {
            document.getElementById("viewMenuDropFollowup").style.display = "block";
        }
    }

加载联系人的代码：

protected void Page_Load(object sender, EventArgs e)    
{
    if (!Page.IsPostBack)
    {
        LoadContacts();
     }    
}

     protected void LoadContacts()
        {
            Customer c = new Customer(int.Parse(CustomerID));

            foreach (Customer.CustomerContact cc in c.Contacts)
            {
                HtmlGenericControl li = new HtmlGenericControl("li");
                CheckBox cb = new CheckBox();
                cb.ID = "cbCRMContact_" + cc.ID;
                cb.Checked = true;
                if (!string.IsNullOrEmpty(cc.Email))
                {
                    cb.Text = cc.Email;
                    cb.TextAlign = TextAlign.Right;
                    li.Controls.Add(cb);
                    ulCRMContacts.Controls.Add(li);
                }
            }

            GetControls(ulCRMContacts.Controls);
        }

我放入行GetControls(ulCRMContacts.Controls);，看看我是否可以得到控件，它在这里工作得很好。但是，当我再次尝试在电子邮件函数中调用GetControls(ulCRMContacts.Controls);时，它返回零。

  protected void btnEmail_Click(object sender, EventArgs e)
        {
            if (EmailFollowup(new lookupCRMCustomerContact(Company.Current.CompanyID, int.Parse(Request.QueryString["CustID"]))))
            {
                DisplayMsg("Follow up has been emailed");
            }
            else
            {
                DisplayMsg("An Error Occurred sending email. Please contact Support");
            }
        }

public bool EmailFollowup(lookupCRMCustomerContact q)
{
      GetControls(ulCRMContacts.Controls);
}

这就像它一离开LoadContacts函数就丢失了ulCRMContacts中的值。