显示最近查看的项目

Question

我有一个 Product 表，其中包含许多产品。我的 HomeController 中有一个详细信息操作方法，它在详细信息视图页面中返回产品详细信息。

假设：我有这些数据：

ProductID | ProductName | Price | CategoryId
    1     |  T-Shirt    |  120  |  Clothing
    2     |   Shirt     |  150  |  Clothing
    3     |   Watch     |  220  |  Watches
    4     |  Laptop     |  820  |  Computing
    5     | Samsung S6  |  520  |  Mobile
    6     |    Xbox     |  320  |  Gaming

现在，我想要的是，如果某些用户访问 T 恤，那么我想将该 T 恤产品添加到“最近浏览”的新 <div> 中。如果他再次访问“手表”，请在“最近浏览”中添加手表产品<div>。

我还想根据他最近浏览的产品展示更多产品。我的意思是，如果他正在访问 Xbox，那么 Xbox 将被添加到最近查看的 <div> 中，并且更多与“游戏”类别相关的产品将显示在最近查看的 <div> 下方的新 <div> 中。

这是我正在尝试的，我的想法是将 productId 存储在 cookie 和详细信息视图页面中，获取 Cookie 请求，从 cookie 获取 productId 并找到该产品的类别并显示更多产品那个类别。

HomeController

public ActionResult Details(int? id)
    {
        if (id == null)
            return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
        Product product = db.Products.Find(id);
        if (product == null)
            return HttpNotFound();

        //Creating cookies
        HttpCookie _userActivity = new HttpCookie("UserActivity");
        _userActivity["ProductID"] = id.ToString();
        _userActivity["ProdutName"] = product.Name;
        _userActivity["Lastvisited"] = DateTime.Now.ToShortTimeString();

        //Adding Expire Time of cookies
        _userActivity.Expires = DateTime.Now.AddDays(5);

        //Adding cookies to current web response
        Response.Cookies.Add(_userActivity);

        //Reading cookies
        HttpCookie readcookie = Request.Cookies["UserActivity"];
        string productID , productName, lastVisited ;
        if (readcookie != null)
        {
            productID = readcookie["ProductID"];
            productName = readcookie["ProdutName"];
            lastVisited = readcookie["Lastvisited"];
        }

        return View(product);
    }

我在我的详细信息视图页面中写了这个。它显示我最近查看产品的 ID 和详细信息，但只有 1 个产品的详细信息来自 cookie。不像我认为的那样

<div class="row">
        <div class="col-sm-9">
            @{
                var product = Request.Cookies["UserActivity"].Values;
            }
            <p>@product</p>

            <br />
            <h2>@Html.DisplayFor(model => model.Name)</h2>
 </div>

Answer 1

首先你应该做一些类来保存你最近的产品信息：

public class RecentProduct
{
    public int ProductId { get; set; }

    public string ProdutName { get; set; }

    public DateTime LastVisited { get; set; }
}

可能在加载时或登录事件的某处用用户持久的最近产品列表填充 Session["RecentProductList"]。

那么你就有了根据提供的信息存储最近产品的功能：

public void AddRecentProduct(List<RecentProduct> list, int id, string name, int maxItems)
{
    // list is current list of RecentProduct objects
    // Check if item already exists
    var item = list.FirstOrDefault(t => t.ProductId == id);
    // TODO: here if item is found, you could do some more coding
    //       to move item to the end of the list, since this is the
    //       last product referenced.
    if (item == null)
    {
        // Add item only if it does not exist
        list.Add(new RecentProduct
        {
            ProductId = id,
            ProdutName = name,
            LastVisited = DateTime.Now,
        });
    }

    // Check that recent product list does not exceed maxItems
    // (items at the top of the list are removed on FIFO basis;
    // first in, first out).
    while (list.Count > maxItems)
    {
        list.RemoveAt(0);
    }
}

然后您可以将控制器的代码最小化以获取详细信息：

public ActionResult Details(int? id)
{
    if (id == null)
        return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
    Product product = db.Products.Find(id);
    if (product == null)
        return HttpNotFound();

    // Read list of recent products from session
    var list = Session["RecentProductList"] as List<RecentProduct>;
    if (list == null)
    {
        // If list not found in session, create list and store it in a session
        list = new List<RecentProduct>();
        Session["RecentProductList"] = list;
    }

    // Add product to recent list (make list contain max 10 items; change if you like)
    AddRecentProduct(list, id.Value, product.Name, 10);

    // Store recentProductList to ViewData keyed as "RecentProductList" to use it in a view
    ViewData["RecentProductList"] = list;
    return View(product);
}

然后在您的视图中从 ViewData 字典中读取数据并显示最近产品列表：

<div class="row">
    <div class="col-sm-9">
        @{
            var recentProductList = ViewData["RecentProductList"] as List<RecentProduct>;
        }
        @* Do whatever you like with recentProductList here (e.g. display its data) *@
        @foreach (var recentProduct in recentProductList)
        {
            <p>@recentProduct.ProdutName (id: @recentProduct.ProductId)</p>
        }

        <br />
        <h2>@Html.DisplayFor(model => model.Name)</h2>
    </div>
</div>

当然，此代码示例缺少一些 null 检查和其他内容，但它应该让您大致了解如何使用此功能。