Hide childnode and only show root node in treeview when first load in ASP.NET

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C#

ASP.NET

I have a problem with my project ,

I was created a treeview menu in my project ,

but i have a problem , i wish when it was load for first time,all of child node is hidden ,and only show root node ,

What I have tried:

this is my code

        <asp:TreeView ID="TreeView1" runat="server">
    <Nodes> 
        <asp:TreeNode Text="Home" NavigateUrl="~/Home.aspx" Target="_blank" />
        <asp:TreeNode Text="Employee" NavigateUrl="~/Employee.aspx" Target="_blank">
            <asp:TreeNode Text="Upload Resume" NavigateUrl="~/UploadResume.aspx" Target="_blank"/>
            <asp:TreeNode Text="Edit Resume" NavigateUrl="~/EditResume.aspx" Target="_blank"/>
            <asp:TreeNode Text="View Resume" NavigateUrl="~/ViewResume.aspx" Target="_blank"/>
        </asp:TreeNode>
        <asp:TreeNode Text="Employer" NavigateUrl="~/   .aspx" Target="_blank">
            <asp:TreeNode Text="Upload Job" NavigateUrl="~/UploadJob.aspx" Target="_blank"/>
            <asp:TreeNode Text="Edit Job" NavigateUrl="~/EditJob.aspx" Target="_blank"/>
            <asp:TreeNode Text="View Job" NavigateUrl="~/ViewJob.aspx" Target="_blank"/>
        </asp:TreeNode>
        <asp:TreeNode Text="Admin" NavigateUrl="~/Admin.aspx" Target="_blank">
            <asp:TreeNode Text="Add User" NavigateUrl="~/AddUser.aspx" Target="_blank"/>
            <asp:TreeNode Text="Edit User" NavigateUrl="~/EditUser.aspx" Target="_blank"/>
            <asp:TreeNode Text="View User" NavigateUrl="~/ViewUser.aspx" Target="_blank"/>
        </asp:TreeNode>
    </Nodes>
</asp:TreeView>