未调用 ActionResult

Question

我有一个视图，我正在调用一个 ActionResult 方法，但在该方法中放置一个断点告诉我它没有被调用。

<div>
<ul class="list-group">
    @foreach (var item in Model)
    {
        <li class="list-group-item">
            <h4>Slide ID: @item.SlideId</h4>
            <p><i>Received: @item.TimeStamp</i></p>
            <div class="row">
                <div class="col-md-4">
                    <h4>@Html.ActionLink("View details", "Well", new {slideid = item.SlideId})</h4>
                    <img src="@Url.Action("Index", "Images", new {id = item.SlideId})"/> //This is where I want to call the method                       
                </div>
            </div>
        </li>
    }
</ul>

方法如下：

public class ImagesController : Controller
{
    // GET: Images
    public ActionResult Index(string id)
    {
        byte[] imageData = new byte[0];
        string cs = "Data Source=" + "some path";

        using (SQLiteConnection con = new SQLiteConnection(cs))
        {
            string stm = "SELECT LastImage FROM Well WHERE SlideId = " + "'" + id + "'";
            con.Open();

            using (SQLiteCommand cmd = new SQLiteCommand(stm, con))
            {
                using (SQLiteDataReader rdr = cmd.ExecuteReader())
                {
                    while (rdr.Read())
                    {
                        imageData = Serialize(rdr["LastImage"]);
                    }

                    rdr.Close();

                }
            }

            con.Close();
        }
        return File(imageData, "image/png");
    }

    public static byte[] Serialize(object obj)
    {
        var binaryFormatter = new BinaryFormatter();
        var ms = new MemoryStream();
        binaryFormatter.Serialize(ms, obj);
        return ms.ToArray();
    }
}

我试图用这段代码实现的是将图像从数据库加载到视图中。关于我做错了什么的任何提示？

现在使用 RouteConfig：

public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );
    }
}

Answer 1

当您编写<img src="@Url.Action("Index", "Images", new {id = item.SlideId})"/> 时，您不会调用操作，而是调用路由 url。结果是一个字符串，例如localhost:8080/images/index/abcd123456，所以，如果你想调用动作，你需要使用@Html.Action("Index", "Images", new {id = item.SlideId})。注意@Html.Action 而不是@Url.Action

Answer 2

我认为与其为每个图像打开和关闭数据库连接，更好的方法是收集所有信息以呈现该页面并将其发送到您发布的视图模型中。假设它称为 HomeController 的 Index 动作。它看起来像这样：

public class HomeController : Controller
{
    public ActionResult Index(string id)
    {
        var listOfItems = new List<SomeClass>();

        string cs = "Data Source=" + "some path";
        using (SQLiteConnection con = new SQLiteConnection(cs))
        {
            string stm = "SELECT SlideId, TimeStamp, LastImage FROM Well"; 
            con.Open();

            using (SQLiteCommand cmd = new SQLiteCommand(stm, con))
            {
                using (SQLiteDataReader rdr = cmd.ExecuteReader())
                {
                    while (rdr.Read())
                    {
                        var someItem = new SomeClass()
                        {
                            SlideId = rdr["SlideId"],
                            ImageData = Serialize(rdr["LastImage"]),
                            TimeStamp = rdr["TimeStamp"]
                        };
                        listOfItems.Add(someItem);
                    }

                    rdr.Close();
                }
            }

            con.Close();
        }

        return View(listOfItems);
    }
}

当然，如果项目太多，您应该始终考虑分页并限制列表中的项目数量以缩短响应时间。