c# - asp.net MVC 4 模型 [Key] 属性无法识别

Question

using System;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity;

//my model
public class Roll
{
    [Key]
    public uint Id { get; set; }
    public long RandomSeed { get; set; }
    public string Expression { get; set; }
    public DateTime DateCreated { get; set; }
    public long Total { get; set; }
}

//my context
public class DiceboxContext : DbContext
{
    public DbSet<Roll> Rolls { get; set; }
}

//my controller 

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace dicebox.Controllers
{
    public class RollController : Controller
    {
        private DiceboxContext db = new DiceboxContext();

        //
        // GET: /Roll/

        public ActionResult Index()
        {
            return View(db.Rolls.ToList());
        }

        //
        // GET: /Roll/Details/5

        public ActionResult Details(int id = 0)
        {
            Roll roll = db.Rolls.Find(id);
            if (roll == null)
            {
                return HttpNotFound();
            }
            return View(roll);
        }

        //
        // GET: /Roll/Create

        public ActionResult Create()
        {
            return View();
        }

        //
        // POST: /Roll/Create

        [HttpPost]
        public ActionResult Create(Roll roll)
        {
            if (ModelState.IsValid)
            {
                db.Rolls.Add(roll);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            return View(roll);
        }

        //
        // GET: /Roll/Edit/5

        public ActionResult Edit(int id = 0)
        {
            Roll roll = db.Rolls.Find(id);
            if (roll == null)
            {
                return HttpNotFound();
            }
            return View(roll);
        }

        //
        // POST: /Roll/Edit/5

        [HttpPost]
        public ActionResult Edit(Roll roll)
        {
            if (ModelState.IsValid)
            {
                db.Entry(roll).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            return View(roll);
        }

        //
        // GET: /Roll/Delete/5

        public ActionResult Delete(int id = 0)
        {
            Roll roll = db.Rolls.Find(id);
            if (roll == null)
            {
                return HttpNotFound();
            }
            return View(roll);
        }

        //
        // POST: /Roll/Delete/5

        [HttpPost, ActionName("Delete")]
        public ActionResult DeleteConfirmed(int id)
        {
            Roll roll = db.Rolls.Find(id);
            db.Rolls.Remove(roll);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        protected override void Dispose(bool disposing)
        {
            db.Dispose();
            base.Dispose(disposing);
        }
    }
}

其中大部分是自动生成的样板代码。每当我点击除 get/Roll/Create 操作之外的任何操作时，它都会崩溃并显示以下错误消息:

System.Data.Entity.Edm.EdmEntityType: : EntityType 'Roll' has no key defined. Define the key for this EntityType.

System.Data.Entity.Edm.EdmEntitySet: EntityType: EntitySet 'Rolls' is based on type 'Roll' that has no keys defined.

但是正如您已经看到的，定义了一个键。还为支持该模型的数据库表“Rolls”定义了一个键。我从谷歌得到的每个答案都建议添加 [Key] 注释，我已经这样做了。

我做错了什么？

Answer 1

将 Id 更改为 int:

public int Id { get; set; }

我将您的代码复制到一个新的 MVC 项目中，搭建了索引、创建和编辑 View ，并且能够毫无问题地创建和编辑卷。