Да уж духотища но я начал хотя бы контроллеры и вьюшки

DatabaseImplement/Models/Sell.cs

@@ -80,5 +80,23 @@ namespace DatabaseImplement.Models
 			DateSell = model.DateSell;
 			UserId = model.UserId;
 		}
+		public void UpdateProducts(Database context, SellBindingModel model)
+		{
+            var sellProducts = context.SellProducts.Where(rec =>
+            rec.Id == model.Id).ToList();
+            if (sellProducts != null && sellProducts.Count > 0)
+            { // удалили те, которых нет в модели
+                context.SellProducts.RemoveRange(sellProducts.Where(rec
+                => !model.SellProducts.ContainsKey(rec.ProductId)));
+                context.SaveChanges();
+                // обновили количество у существующих записей
+                foreach (var updateProduct in sellProducts)
+                {
+                    updateProduct.Count = model.SellProducts[updateProduct.ProductId].Item2;
+                    model.SellProducts.Remove(updateProduct.ProductId);
+                }
+                context.SaveChanges();
+            }
+        }
 	}
 }

RestAPI/Controllers/MainController.cs

@@ -0,0 +1,78 @@
+using BusinessLogic.BusinessLogic;
+using Contracts.BindingModels;
+using Contracts.BusinessLogicContracts;
+using Contracts.Exceptions;
+using Contracts.SearchModels;
+using Contracts.ViewModels;
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.AspNetCore.Mvc;
+
+namespace RestAPI.Controllers
+{
+    [Route("[controller]/[action]")]
+    [ApiController]
+    public class MainController
+    {
+        private readonly ILogger _logger;
+        private readonly IProductLogic _product;
+
+        public MainController(ILogger<MainController> logger, IProductLogic productLogic)
+        {
+            _logger = logger;
+            _product = productLogic;
+        }
+        [HttpGet]
+        public List<ProductViewModel>? GetProductList()
+        {
+            try
+            {
+                return _product.ReadList(null);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Ошибка получения списка пакетов");
+                throw;
+            }
+        }
+
+        [HttpPatch]
+        public IResult Update([FromBody] ProductBindingModel model)
+        {
+            try
+            {
+                var res = _product.Update(model);
+                return Results.Ok(res);
+            }
+            catch (AccountException ex)
+            {
+                _logger.LogWarning(ex, "Wrong update data");
+                return Results.BadRequest(ex.Message);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error update user");
+                return Results.Problem(ex.Message);
+            }
+        }
+
+        [HttpDelete]
+        public IResult Delete(Guid id)
+        {
+            try
+            {
+                var res = _product.Delete(new() { Id = id });
+                return Results.Ok(res);
+            }
+            catch (ElementNotFoundException ex)
+            {
+                _logger.LogInformation(ex, "User not found");
+                return Results.NoContent();
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error delete user");
+                return Results.Problem(ex.Message);
+            }
+        }
+    }
+}

WebApp/Pages/Catalog.cshtml

@@ -1,4 +1,56 @@
 @page
 @model WebApp.Pages.CatalogModel
 @{
+    ViewData["Title"] = "Каталог оружия";
+}
+<!-- Шапка -->
+<nav class="navbar navbar-expand-lg navbar-light bg-light">
+    <a class="navbar-brand" href="#">Catalog</a>
+    <div class="collapse navbar-collapse">
+        <ul class="navbar-nav mr-auto">
+            <li class="nav-item dropdown">
+                <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
+                    Категории
+                </a>
+                <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
+                    <a class="dropdown-item" href="#">Пистолеты</a>
+                    <a class="dropdown-item" href="#">Револьверы</a>
+                    <a class="dropdown-item" href="#">Винтовки</a>
+                </div>
+            </li>
+        </ul>
+        <form method="get">
+            <div class="form-inline col-lg-12">
+                <input class="form-control mr-sm-2" type="search" placeholder="Поиск" name="search" value="">
+                <button class="btn btn-outline-success" type="submit"><i class="fas fa-search"></i></button>
+            </div>
+        </form>
+        <div class="form-group">
+            <form method="get" m>
+                <input type="range" step="100" min="0" max="10000" value="50000" class="custom-range" id="priceFrom">
+                <label for="priceFrom">От: <span id="priceLabelFrom">50 000</span> руб.</label>
+            </form>
+
+            <form method="get">
+                <input type="range" step="100" min="0" max="100000" value="50000" class="custom-range" id="priceTo">
+                <label for="priceTo">До: <span id="priceLabelTo">50 000</span> руб.</label>
+            </form>
+        </div>
+    </div>
+</nav>
+
+@section Scripts {
+    <script>
+        document.getElementById("priceFrom").addEventListener("input", function () {
+            var price = this.value;
+            document.getElementById("priceLabelFrom").textContent = price + " руб.";
+            // Здесь должен быть код для фильтрации товаров по цене
+        });
+
+        document.getElementById("priceTo").addEventListener("input", function () {
+            var price = this.value;
+            document.getElementById("priceLabelTo").textContent = price + " руб.";
+            // Здесь должен быть код для фильтрации товаров по цене
+        });
+    </script>
 }

WebApp/Pages/Shared/_Layout.cshtml

@@ -7,6 +7,10 @@
     <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="~/WebApp.styles.css" asp-append-version="true" />
+    <script src="https://code.jquery.com/jquery-3.5.1.slim.min.js"></script>
+    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js"></script>
+    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>
+    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0-beta3/css/all.min.css">
 </head>
 <body>
     <header>
@@ -23,10 +27,16 @@
                             <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>
+                            <a class="nav-link text-dark" asp-area="" asp-page="/Catalog">Catalog</a>
                         </li>
+                        @* <li class="nav-item">
+                            <a class="nav-link text-dark" asp-area="" asp-page="/Privacy">Privacy</a>
+                        </li>  *@                 
                         @if (User.Identity.IsAuthenticated)
                         {
+                            <li class="nav-item">
+                                <a class="nav-link text-dark" asp-area="" asp-page="/Cart">Cart</a>
+                            </li>
                             <li class="nav-item">
                                 <a class="nav-link text-dark" asp-area="" asp-page="/User/Index">Profile</a>
                             </li>