Untitled

@page
@model MyProject.NavBarModel

<div class="collapse navbar-collapse" id="navbarNavAltMarkup">
    <ul class="navbar-nav">
        <li class="nav-item"><a class="nav-link" asp-page="/Machines">@Resources.Machines</a></li>
        <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">@Resources.Orders</a>
            <div class="dropdown-menu" aria-labelledby="navbarDropdown">
                <a class="dropdown-item" asp-page="/RunningOrders">@Resources.Running <span class="badge badge-primary">@ViewData["running"]</span></a>
                <a class="dropdown-item" asp-page="/OpenOrders">@Resources.Opened <span class="badge badge-primary">@ViewData["running"]</span></a>
                <div class="dropdown-divider"></div>
                <a class="dropdown-item" asp-page="/SuspendedOrders">@Resources.Suspended <span class="badge badge-danger">@ViewData["running"]</span></a>
            </div>
        </li>
        <li class="nav-item"><a class="nav-link" asp-page="/Tables">@Resources.Lists</a></li>
        <li class="nav-item"><a class="nav-link" asp-page="/About">@Resources.About</a></li>
    </ul>
</div>

using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.EntityFrameworkCore;
using MyProject.Models;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace MyProject
{
    public class NavBarModel : PageModel
    {
        private readonly MyContext _context;

        public NavBarModel(MyContext context)
        {
            _context = context;
        }

        public List<Order> Orders { get; set; }

        public async Task OnGetAsync()
        {
            Orders = await _context.Orders.ToListAsync();

            ViewData["open"] = _context.Orders.Where(x => x.State == OrderStates.Open).Count();
            ViewData["running"] = _context.Orders.Where(x => x.State == OrderStates.Running).Count();
            ViewData["suspened"] = _context.Orders.Where(x => x.State == OrderStates.Suspended).Count();
        }
    }
}

<body>
    <nav class="navbar navbar-expand-lg navbar-dark bg-dark fixed-top mb-2">
        <a asp-page="/Index" class="navbar-brand">Production Assistant</a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavAltMarkup" aria-controls="navbarNavAltMarkup" aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>
        @Html.Partial("NavBar", new NavBarModel())

    </nav>
    <div class="container body-content">
        @RenderBody()
    </div>
</body>