Navigation Dropdowns in ASP.NET Core 8.0 Razor Pages - How to prevent opening new pages?

I am developing an ASP.NET Core 8.0 application using Razor Pages. I have implemented a dynamic navigation menu that needs to be consistently displayed across all pages of my application. The navigation menu items are fetched dynamically based on the user's role from a database.

I have successfully implemented a navigation menu using Razor Pages and I'm currently displaying it on a dedicated Main.cshtml page. However, when a user navigates to another page, the new page opens independently of the navigation menu, which I want to remain consistent across all pages.

Main.cshtml code:

  <ul class="horizontal-list ">
      @foreach (var menuItem in Model.MenuItems.Where(m => m.parentId == null))
      {
          <li>
              <a class="dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">@menuItem.formName</a>
              <ul class="dropdown-menu">
                  @foreach (var subMenuItem in Model.MenuItems.Where(m => m.parentId == menuItem.formID))
                  {
                      @if (Model.MenuItems.Any(m => m.parentId == subMenuItem.formID))
                      {
                          <li class="dropdown-submenu">
                              <a class="dropdown-item dropdown-toggle menutext" href="#">@subMenuItem.formName</a>
                              <ul class="dropdown-menu">
                                  @foreach (var subsubMenuItem in Model.MenuItems.Where(m => m.parentId == subMenuItem.formID))
                                  {
                                      <li class="dropdown-menu-1">
                                        <a class="dropdown-item menutext" href="@subsubMenuItem.formUrl">@subsubMenuItem.formName</a>
                                      </li>
                                  }
                              </ul>
                          </li>
                      }
                      else
                      {
                          <li class="dropdown-submenu">
                              <a class="dropdown-item menutext" href="@subMenuItem.formUrl">@subMenuItem.formName</a>
                          </li>
                      }
                  }
              </ul>
          </li>
      }
  </ul>

Main.cshtml.cs code:

public List<Menu> GetMenusForRole(long roleId)
{
    var menuList = new List<Menu>();
    
    // Example logic to fetch menus based on roleId from a database
    ArrayList parameters = new ArrayList { roleId };
    DataTable dtMenus = ExecuteStoredProcedure.ExecProc_getDataTable(_configuration, "Stored_Procedure_Name", parameters);
    
    foreach (DataRow row in dtMenus.Rows)
    {
        menuList.Add(new Menu
        {
            formID = Convert.ToInt64(row["Form_ID"].ToString()),
            formName = row["Form_Title"].ToString(),
            parentId = row["Form_Parent_ID"] == DBNull.Value ? (long?)null : Convert.ToInt64(row["Form_Parent_ID"].ToString()),
            formUrl = row["Form_Url"].ToString()
        });
    }
    
    return menuList;
}

What I've Tried Initially, I created a Main.cshtml and Main.cshtml.cs to display the navigation dropdowns, but this approach leads to the new pages opening independently. I attempted to move the navigation bar into the _Layout.cshtml file, which is used as the main layout template across all pages. However, since the menu items are dynamically fetched based on user roles, I encountered difficulties because _Layout.cshtml does not directly support backend logic.

Desired Outcome: I want to have a navigation menu that remains fixed across all pages of my application, where each menu item is dynamically fetched based on the user's role. When a user navigates to a new page, I want this page to be displayed within the context of the navigation menu, without the menu itself being refreshed.

you could try to place the navigation menu in the _Layout.cshtml file as it does not support backend logic, you will need to make use of a combination of dependency injection and a view component.

NavigationMenuViewComponent.cs:
using DynamicMenuProject.Data;
using DynamicMenuProject.Models;
using Microsoft.AspNetCore.Mvc;

namespace DynamicMenuProject.Pages.Components
{
    public class NavigationMenuViewComponent : ViewComponent
    {
        private readonly ApplicationDbContext _context;

        public NavigationMenuViewComponent(ApplicationDbContext context)
        {
            _context = context;
        }

        public async Task<IViewComponentResult> InvokeAsync()
        {
            var roleId = GetUserRoleId(); // Implement this method to get the current user's role ID
            var menuItems = await Task.Run(() => GetMenusForRole(roleId));

            return View(menuItems);
        }

        private List<Menu> GetMenusForRole(long roleId)
        {
            return _context.Menus
                           .Where(m => m.Role_Id == roleId)
                           .Select(m => new Menu
                           {
                               Form_ID = m.Form_ID,
                               Form_Title = m.Form_Title,
                               Form_Parent_ID = m.Form_Parent_ID,
                               Form_Url = m.Form_Url ?? string.Empty, // Provide a default value for NULL URLs
                               Role_Id = m.Role_Id
                           })
                           .ToList();
        }


        private long GetUserRoleId()
        {
            // Implement logic to retrieve the current user's role ID
            return 1; // Example role ID
        }

    }
}

Views/Shared/Components/NavigationMenu/Default.cshtml:

@model List<DynamicMenuProject.Models.Menu>

<ul class="navbar-nav me-auto mb-2 mb-lg-0">
    @foreach (var menuItem in Model.Where(m => m.Form_Parent_ID == null))
    {
        <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown_@menuItem.Form_ID" role="button" data-bs-toggle="dropdown" aria-expanded="false">@menuItem.Form_Title</a>
            <ul class="dropdown-menu" aria-labelledby="navbarDropdown_@menuItem.Form_ID">
                @foreach (var subMenuItem in Model.Where(m => m.Form_Parent_ID == menuItem.Form_ID))
                {
                    @if (Model.Any(m => m.Form_Parent_ID == subMenuItem.Form_ID))
                    {
                        <li class="dropdown-submenu">
                            <a class="dropdown-item dropdown-toggle" href="#">@subMenuItem.Form_Title</a>
                            <ul class="dropdown-menu">
                                @foreach (var subsubMenuItem in Model.Where(m => m.Form_Parent_ID == subMenuItem.Form_ID))
                                {
                                    <li>
                                        <a class="dropdown-item" href="@subsubMenuItem.Form_Url">@subsubMenuItem.Form_Title</a>
                                    </li>
                                }
                            </ul>
                        </li>
                    }
                    else
                    {
                        <li>
                            <a class="dropdown-item" href="@subMenuItem.Form_Url">@subMenuItem.Form_Title</a>
                        </li>
                    }
                }
            </ul>
        </li>
    }
</ul>

_Layout.cshtml:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>@ViewData["Title"] - DynamicMenuProject</title>
    <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.min.css" />
    <link rel="stylesheet" href="~/css/site.css" asp-append-version="true" />
    <link rel="stylesheet" href="~/DynamicMenuProject.styles.css" asp-append-version="true" />
</head>
<body>
    <header>
        <nav class="navbar navbar-expand-sm navbar-toggleable-sm navbar-light bg-white border-bottom box-shadow mb-3">
            <div class="container">
                <a class="navbar-brand" asp-area="" asp-page="/Index">DynamicMenuProject</a>
                <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
                    <span class="navbar-toggler-icon"></span>
                </button>
                <div class="collapse navbar-collapse" id="navbarNav">
                    <ul class="navbar-nav">
                        <li class="nav-item">
                            <a class="nav-link text-dark" asp-area="" asp-page="/Index">Home</a>
                        </li>
                        <li class="nav-item">
                            <a class="nav-link text-dark" asp-area="" asp-page="/Privacy">Privacy</a>
                        </li>
                    </ul>
                    <!-- Render the dynamic navigation menu -->
                    @await Component.InvokeAsync("NavigationMenu")
                </div>
            </div>
        </nav>
    </header>
    <div class="container">
        <main role="main" class="pb-3">
            @RenderBody()
        </main>
    </div>

    <footer class="border-top footer text-muted">
        <div class="container">
            &copy; 2024 - DynamicMenuProject - <a asp-area="" asp-page="/Privacy">Privacy</a>
        </div>
    </footer>

    <script src="~/lib/jquery/dist/jquery.min.js"></script>
    <script src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js"></script>
    <script src="~/js/site.js" asp-append-version="true"></script>

    @await RenderSectionAsync("Scripts", required: false)
</body>
</html>