为什么我不能从MVC访问新产品列表？

Question

Hi! i try to learn Asp.net MVC.i created a sample application to learn it. But press f5 return server error. Where do l make a mistake? where is the problem? there is a navigator bar Home/About/Product . if i press Product, error return to me.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using MvcApplication1.Models.Db;

namespace MvcApplication1.Controllers
{
    public class ProductsController : Controller
    {
        //
        // GET: /Products/

        public ActionResult GetAll()
        {
            using (var ctx = new MyDbEntities())
            {
                ViewData["Products"] = ctx.Products;
                return View();
            }

        }

    }
}

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MvcApplication1.Models.Db.Product>" %>
<%@ Import Namespace="MvcApplication1.Models.Db" %>
<%@ Import Namespace="MvcApplication1.Controllers" %>
<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
    ProductDetail
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

    <h2>ProductDetail</h2>
    <ul>

<% foreach (var m in (IEnumerable<Products>)ViewData["Products"])
     { %>

     <li><%= m.ProductName %></li>

<% } %>
</ul>

</asp:Content>

            <div id="menucontainer">

                <ul id="menu">              
                    <li><%: Html.ActionLink("Home", "Index", "Home")%></li>
                    <li><%: Html.ActionLink("About", "About", "Home")%></li>
                     <li><%: Html.ActionLink("Product", "ProductDetail", "Product")%></li>
                </ul>

            </div>

Answer 1

<%: Html.ActionLink("Product", "ProductDetail", "Product")%>

the action name ProductDetail is not in your controller you have GetAll action name

u need

 public ActionResult ProductDetail()
    {
        using (var db = new NorthwindEntities())
        {
            return View(db.Products.ToList());
        }
    }

Answer 2

Can you provide more information such as the actual server error?

Quickly looking at the code the View name is wrong. going to /Products/ expects a view named Products not product details.

Answer 3

There is a mismatch between the Controller name and the View folder name. Also between the Action name and the View name.

Products Controller -> Product Folder in Views

GetAll Action -> ProductDetail.aspx View

Rename to:

Product Controller -> Product Folder in Views

ProductDetail Action -> ProductDetail.aspx View

Also, make this line:

ViewData["Products"] = ctx.Products;

like this:

ViewData["Products"] = ctx.Products.ToList();

Your views shouldn't be making calls to the database.

Answer 4

Assuming you doing the default routing.

1. The Problem is that your controller is named ProductsController (pluralized). Change the name to ProductController or the name of the viewfolder to Products .

2. Another problem is that your Controller does not contain a ActionMethod ProductDetail , your link in the site.Master pointing to ProductController.ProductDetail

If you want to learn Asp.NET Mvc i encourage you to check out the following tutorials.

• NerdDinner Tutorial
• MVC/Tutorials/Chapter 3. MVC Music Store
• Asp.NET MVC

hope this helps

Answer 5

First of all, try to be more specific. What error do you get?

Now, I think I see what the problem is, but I'm just guessing because you didn't post the error. For what I see, you pass to the view the IQueryable: ctx.Products without enumerating it.

Then the view tries to enumerate it, but the context is disposed, so the query cannot run. I guess the error you're getting is something like "the context is not available" or something like this.

First of all, try to change the statement like this: ctx.Products.ToList() and see if the error goes away.

Another thing I spotted you're using the dictionary, while using a strongly typed ViewModel would be much better (or at least use dynamic).

Answer 6

if you do not specify a View name, the application will look for a view with the name of your method. Ie:

public ActionResult GetAll()
    {
        using (var ctx = new MyDbEntities())
        {
            ViewData["Products"] = ctx.Products;
            return View();
        }

    }

Is looking for a view "Product/GetAll.aspx". Solutions:

• change the name of the method
• change the name of the view
• Specify the view name by doing return View("ProductDetail");