未调用ActionResult

Question

我有一个视图，在这个视图中我调用了一个ActionResult方法，但是在该方法中放置一个断点就会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>

​

下面是方法：

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一个图像从数据库加载到视图中。有什么关于我哪里做错了的提示吗？

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，因此，如果您想调用操作，则需要使用@Html.Action("Index", "Images", new {id = item.SlideId})。注意，不是@Url.Action，而是@Html.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来呈现该页面，并将其发送到您发布的视图模型中。假设它被称为HomeController的索引操作。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，如果条目太多，您应该始终考虑分页，并限制列表中条目的数量，以缩短响应时间。