过去几周我一直在学习 MVC 5。到目前为止，直到昨天，我几乎没有遇到任何问题。一切都工作正常，直到昨晚我打开 VS 来处理我的项目。
我的问题:
为了解决一些问题，我重新启动了计算机，修复了 VS 安装，从 AppData 中删除了临时文件夹等。我已经用尽了我能找到的所有可能的解决方案。现在谈谈我的问题。
首先，我停止了当前的项目，并使用相同的数据库模型创建了一个新项目。该数据库是 Azure SQL 数据库。对于每个对象，我创建了自己的类来应用如下所示的数据注释:(我删除了所有数据注释，因为数据注释数量相当多。错误仍然存在)
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
namespace Dyad.GreenvilleFoodTrucks.Data
{
[MetadataType(typeof(LocationMetadata))]
public partial class Location
{
}
public class LocationMetadata
{
public int ID { get; set; }
public int TruckID { get; set; }
public Nullable<System.DateTime> StartTime { get; set; }
public Nullable<System.DateTime> EndTime { get; set; }
public Nullable<System.DateTime> Date { get; set; }
public string Description { get; set; }
public string Address { get; set; }
public string State { get; set; }
public string ZIP { get; set; }
public virtual Truck Truck { get; set; }
}
}
以及从我的数据库创建的对象 EF:
namespace Dyad.GreenvilleFoodTrucks.Data
{
using System;
using System.Collections.Generic;
public partial class Location
{
public int ID { get; set; }
public int TruckID { get; set; }
public Nullable<System.DateTime> StartTime { get; set; }
public Nullable<System.DateTime> EndTime { get; set; }
public Nullable<System.DateTime> Date { get; set; }
public string Description { get; set; }
public string Address { get; set; }
public string State { get; set; }
public string ZIP { get; set; }
public virtual Truck Truck { get; set; }
}
}
然后，我使用新创建的模型创建了一个脚手架项目，其中上下文是 EF 创建的上下文，而不是 ApplicationDBContext。
现在，当我进入生成的 View 时， ViewBag.Title = "title";给我这个错误: “找不到编译动态表达式所需的一个或多个类型。您是否缺少引用？”请注意，这种情况发生在所有 CRUD cshtml 文件以及索引上。
除此之外，在每个 @Html.LabelFor/@Html.DisplayNameFor 以及任何以“For”结尾的内容上都会出现此错误: “无法从用法中推断出方法“System.Web.Mvc.Html.DisplayNameExtensions.DisplayNameFor(System.Web.Mvc.HtmlHelper, System.Linq.Expressions.Expression>)”的类型参数。尝试显式指定类型参数”
这是 View 的样子。这都是自动生成的，所以我没有更改任何内容。
@model Dyad.GreenvilleFoodTrucks.Data.Location
@{
ViewBag.Title = "Create";
}
<h2>Create</h2>
@using (Html.BeginForm())
{
@Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>Location</h4>
<hr />
@Html.ValidationSummary(true, "", new { @class = "text-danger" })
<div class="form-group">
@Html.LabelFor(model => model.TruckID, "TruckID", htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.DropDownList("TruckID", null, htmlAttributes: new { @class = "form-control" })
@Html.ValidationMessageFor(model => model.TruckID, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.StartTime, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.StartTime, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.StartTime, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.EndTime, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.EndTime, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.EndTime, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.Date, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.Date, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.Date, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.Description, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.Description, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.Description, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.Address, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.Address, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.Address, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.State, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.State, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.State, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
@Html.LabelFor(model => model.ZIP, htmlAttributes: new { @class = "control-label col-md-2" })
<div class="col-md-10">
@Html.EditorFor(model => model.ZIP, new { htmlAttributes = new { @class = "form-control" } })
@Html.ValidationMessageFor(model => model.ZIP, "", new { @class = "text-danger" })
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}
<div>
@Html.ActionLink("Back to List", "Index")
</div>
@section Scripts {
@Scripts.Render("~/bundles/jqueryval")
}
及其 Controller :
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Linq;
using System.Net;
using System.Web;
using System.Web.Mvc;
using Dyad.GreenvilleFoodTrucks.Data;
namespace Dyad.GreenvilleFoodTrucks.Controllers
{
public class LocationsController : Controller
{
private GreenvilleFoodTrucksEntities db = new GreenvilleFoodTrucksEntities();
// GET: Locations
public ActionResult Index()
{
var locations = db.Locations.Include(l => l.Truck);
return View(locations.ToList());
}
// GET: Locations/Details/5
public ActionResult Details(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Location location = db.Locations.Find(id);
if (location == null)
{
return HttpNotFound();
}
return View(location);
}
// GET: Locations/Create
public ActionResult Create()
{
ViewBag.TruckID = new SelectList(db.Trucks, "ID", "Name");
return View();
}
// POST: Locations/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Include = "ID,TruckID,StartTime,EndTime,Date,Description,Address,State,ZIP")] Location location)
{
if (ModelState.IsValid)
{
db.Locations.Add(location);
db.SaveChanges();
return RedirectToAction("Index");
}
ViewBag.TruckID = new SelectList(db.Trucks, "ID", "Name", location.TruckID);
return View(location);
}
// GET: Locations/Edit/5
public ActionResult Edit(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Location location = db.Locations.Find(id);
if (location == null)
{
return HttpNotFound();
}
ViewBag.TruckID = new SelectList(db.Trucks, "ID", "Name", location.TruckID);
return View(location);
}
// POST: Locations/Edit/5
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit([Bind(Include = "ID,TruckID,StartTime,EndTime,Date,Description,Address,State,ZIP")] Location location)
{
if (ModelState.IsValid)
{
db.Entry(location).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
ViewBag.TruckID = new SelectList(db.Trucks, "ID", "Name", location.TruckID);
return View(location);
}
// GET: Locations/Delete/5
public ActionResult Delete(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
Location location = db.Locations.Find(id);
if (location == null)
{
return HttpNotFound();
}
return View(location);
}
// POST: Locations/Delete/5
[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public ActionResult DeleteConfirmed(int id)
{
Location location = db.Locations.Find(id);
db.Locations.Remove(location);
db.SaveChanges();
return RedirectToAction("Index");
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
db.Dispose();
}
base.Dispose(disposing);
}
}
}
解决了所有这些问题后，我还想指出，当我以管理员身份运行 VS 时，这一切都不会发生，这是我不明白的。此外，每个都照常编译和运行。
我为冗长的文章表示歉意，但我不想遗漏任何内容。如果我误用了任何术语，我也深表歉意，因为我对 MVC 和 C# 总体来说还很陌生。
如果我还可以添加任何其他内容，请告诉我。
最佳答案
当 View 文件夹中的 web.config 文件引用旧版本或缺失版本的 MVC 或 Razor 依赖项时，有时会发生这种情况。如果您无法手动修复它，或者找出哪个引用有问题，最简单的方法是创建一个新的 MVC 项目，并将 View 文件夹中的 web.config 文件与现有项目的配置文件进行比较。
虽然它在运行或调试时通常不会破坏任何东西，但它确实让 Intellisense 感到困惑。
关于c# - MVC 5 - 无法从用法推断方法 "..."的类型参数。尝试显式指定类型参数，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26346053/