How to use Sub Menu in Blazor

How to use Sub Menu in Blazor:

NavMenu.razor:

<div class="top-row pl-4 navbar navbar-dark">

    <a class="navbar-brand" href="">Sub Menu Demo</a>

    <button class="navbar-toggler" @onclick="ToggleNavMenu">

        <span class="navbar-toggler-icon"></span>

    </button>

</div>

<div class="@NavMenuCssClass" @onclick="ToggleNavMenu">

    <ul class="nav flex-column">

        <li class="nav-item px-3">

            <NavLink class="nav-link" href="" Match="NavLinkMatch.All">

                <span class="oi oi-home" aria-hidden="true"></span> Home

            </NavLink>

        </li>

        <li class="nav-item px-3">

            <NavLink class="nav-link" href="counter">

                <span class="oi oi-plus" aria-hidden="true"></span> Counter

            </NavLink>

        </li>

        <li class="nav-item px-3">

            <NavLink class="nav-link" href="cart" @onclick="()=>expandSubMenu= !expandSubMenu">

                <span class="oi oi-cart" aria-hidden="true"></span> Cart

            </NavLink>

            @if (expandSubMenu)

            {

                <ul class="nav flex-column">

                    <li class="nav-item px-3">

                        <NavLink class="nav-link" href="cart/1">

                            <span class="oi oi-file" aria-hidden="true"></span> Sub-1

                        </NavLink>

                    </li>

                    <li class="nav-item px-3">

                        <NavLink class="nav-link" href="cart/2">

                            <span class="oi oi-bar-chart" aria-hidden="true"></span> Sub-1

                        </NavLink>

                    </li>

                </ul>

            }

        </li>

        <li class="nav-item px-3">

            <NavLink class="nav-link" href="fetchdata">

                <span class="oi oi-list-rich" aria-hidden="true"></span> Fetch data

            </NavLink>

        </li>

    </ul>

</div>

@code {

    private bool collapseNavMenu = true;

    private bool expandSubMenu;//add

    private string NavMenuCssClass => collapseNavMenu ? "collapse" : null;

    private void ToggleNavMenu()

    {

        collapseNavMenu = !collapseNavMenu;

    }

}

Dynamic Menu:

https://ashproghelp.blogspot.com/2020/05/load-menu-sub-menu-from-database-in.html

For Details please follow this video:
(Please Subscribe my Channel-AshProgHelp)
Load Menu & Sub Menu From Database in Blazor :
https://www.youtube.com/watch?v=aGn3oYAmj4w
How to use Sub Menu in Blazor:
https://www.youtube.com/watch?v=prz5kATC1Dg
Dapper CRUD in Blazor:
https://www.youtube.com/watch?v=nsZNCr7q4gE