Getting Error : System.InvalidOperationException: User-Unhandled

Question

我正在尝试学习使用 ASP.NET MVC 5 和 Entity Framework 构建一个简单的应用程序。我能够添加迁移并更新数据库。我的应用程序在执行时工作正常。下面是我的应用程序的以下代码。

客户控制器：

using System.Linq;
using System.Web.Mvc;
using WebChatApp.Models;
using System.Data.Entity;

namespace WebChatApp.Controllers
{
    public class CustomersController : Controller
    {
        private ApplicationDbContext _context;

        public CustomersController()
        {
            _context = new ApplicationDbContext();
        }
        protected override void Dispose(bool disposing)
        {
            _context.Dispose();
        }

        // GET: Customers
        public ViewResult Index()
        {
            var customers = _context.Customers.Include(c => c.MembershipType).ToList();


            return View(customers);
        }
        public ActionResult Details(int id)
        {
            var customer = _context.Customers.SingleOrDefault(c => c.Id == id);

            if (customer == null)
                return HttpNotFound();
            return View(customer);
        }


    }
}

型号：

using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web;

namespace WebChatApp.Models
{
    public class Customer
    {
        public int Id { get; set; }
        [Required]
        [StringLength(255)]
        public string Name { get; set; }
        public bool IsSubscribedToNewsletter { get; set; }
        public MembershipType MembershipType { get; set; }

        public byte MembershipTypeId { get; set; }
    }
}

客户视图：

@model IEnumerable<WebChatApp.Models.Customer>
@{
    ViewBag.Title = "Customers";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h2>Customers</h2>
@if (!Model.Any())
{
        <p>We don't have any customer yet.</p>
}
else
{
    <table class=" table table-bordered table-hover">
        <thead>
            <tr>
                <th>Customer</th>
                <th>Membership Type</th>
                </tr>
            </thead>
        <tbody>
            @foreach (var customer in Model)
            {
                <tr>
                    <td>@Html.ActionLink(customer.Name, "Details","Customers", new { id = customer.Id }, null)</td>
                    <td>@customer.MembershipType.Name</td>    
                </tr>
            }
            </tbody>
        </table>
}

迁移：

SQL 服务器中的表：

当我尝试执行执行并从 NavBar 导航到客户模块时，出现以下错误。

System.InvalidOperationException: 'The model backing the 'ApplicationDbContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269).'

var customers = _context.Customers.Include(c => c.MembershipType).ToList();

异常图像：

甚至我通过将目标数据库更新到 DBContext 来检查来自 PackageManagerConsole 的 Entity Framework。即使我已经浏览了 Whosebug 中的一些旧线程。但它对我不起作用。有人可以帮忙吗？

Answer 1

您的数据库模型（出于某种原因）与您的模型不同步。您可以尝试在程序包管理器控制台中运行：add-migration test 并查看它是否会产生新的迁移。如果是，您只需运行 update-database 之后。

如果这没有帮助，请查看此答案：

Getting Error : System.InvalidOperationException: User-Unhandled

Getting Error : System.InvalidOperationException: User-Unhandled

c#

asp.net

razor

entity-framework-6

asp.net-mvc-5