Null reference exception thrown on attempt to dynamically populate ASP.NET MenuItem

Question

I'm trying to populate an ASP Menu with ASP MenuItems dynamically from the code behind, but am getting an object reference is not set to an instance of an object exception.

This is what my ASP looks like:

<asp:Menu ID="HeaderMenu" runat="server">
    <Items>
    </Items>
</asp:Menu>

And this is what my code behind looks like:

protected void Page_Load(object sender, EventArgs e)
{
    PopulateMenu();
}

protected void PopulateMenu()
{
    HeaderMenu.Items.Add(new MenuItem 
    {
        Text = "Register Now!",
        NavigateUrl = "~/Pages/Register.aspx"
    });
}

It's throwing the exception on calling Add, but I can't figure out why.

EDIT: PopulateMenu() is being called on page load

Welcome to Stack Overflow! Almost all cases of `NullReferenceException` are the same. Please see "[What is a NullReferenceException in .NET?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-in-net)" for some hints. — John Saunders, Apr 17 '13 at 04:25
I bet that `HeaderMenu.Items == null`, assuming that `HeaderMenu != null` — John Saunders, Apr 17 '13 at 04:26

score 0 · Answer 1 · answered Apr 17 '13 at 05:29

try this

<asp:Menu ID="HeaderMenu" runat="server">
    <Items>
    </Items>
</asp:Menu>


protected void Page_Load(object sender, EventArgs e)
{
    PopulateMenu();
}

protected void PopulateMenu()
{
    HeaderMenu.Items.Add(new MenuItem 
    {
        "Register Now!",
        "","", 
        "~/Pages/Register.aspx"
    });
}

Null reference exception thrown on attempt to dynamically populate ASP.NET MenuItem

1 Answers1