Question

我正在尝试创建一个viewmodel，以便我可以在一个页面上显示从多个模型收集的信息，但是我遇到了多个错误（如下所示）因为所使用的模型是我解决方案中不同项目的一部分。任何帮助将不胜感激。除了显示我试图创建用户创建时的下拉列表的信息，他们还可以选择每个用户使用的设备。

User.cs（型号）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
using System.Collections.Generic;

namespace FaceToFace.Model
{
    public class User
    {
        public int UserID { get; set; }
        public string CodeName { get; set; }
        public bool UseBriefInstructions { get; set; }
        public ICollection<RegimeItem> RegimeItems { get; set; }
        public Device Device { get; set; }
        public virtual ICollection<Grading> UserGradings { get; set; }

        public User()
        {
            this.RegimeItems = new List<RegimeItem>();
            Device = new Device();
        }


    }

Device.cs（型号）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FaceToFace.Model
{
    public class Device
    {
        public int DeviceID { get; set; }
        public string Name { get; set; }
    }
}

UserDeviceViewModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.WebPages.Html;
using FaceToFace.Model;

namespace FaceToFaceWebsite.Models
{
    public class UserDeviceViewModel
    {
        public UserDeviceViewModel()
        {
            User = new User();
            Users = new List<User>();
            Devices = new List<SelectListItem>();
        }

        public User UseBriefInstructions { get; set; }
        public Device Device { get; set; }
        public User User { get; set; }
        public User CodeName { get; set; }
        public IList<SelectListItem> Devices { get; set; }
        public IList<User> Users { get; set; }
    }
}

查看/患者/ Create.cshtml

    @model FaceToFace.Model.User

    @{
        ViewBag.Title = "Create";
    }

    <h2>Create</h2>

    @using (Html.BeginForm()) {
        @Html.AntiForgeryToken()
        @Html.ValidationSummary(true)

        <fieldset>
            <legend>User</legend>

            <div class="editor-label">
                @Html.LabelFor(model => model.CodeName)
            </div>
            <div class="editor-field">
                @Html.EditorFor(model => model.CodeName)
                @Html.ValidationMessageFor(model => model.CodeName)
            </div>

            <div class="editor-label">
                @Html.LabelFor(model => model.Device.Name, "Device")
            </div>
            <div class="editor-field">
                @Html.DropDownListFor(model => model.User.Device.DeviceID, Model.Devices)
        <input type="submit" value="Save" />
            </div>

            <div class="editor-label">
                @Html.LabelFor(model => model.UseBriefInstructions)
            </div>
            <div class="editor-field">
                @Html.EditorFor(model => model.UseBriefInstructions)
                @Html.ValidationMessageFor(model => model.UseBriefInstructions)
            </div>

            <p>
                <input type="submit" value="Create" />
            </p>
        </fieldset>
    }

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

PatientController.cs

 using System;
using System.Collections;
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 FaceToFace.Model;
using System.ComponentModel.DataAnnotations;
using FaceToFaceWebsite.Models;

namespace FaceToFaceWebsite.Controllers
{
    public class PatientController : Controller
    {
        private F2FData db = new F2FData();

        //
        // GET: /Patient/
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Index(UserDeviceViewModel viewModelDevice)
        {

            var viewModel = new UserDeviceViewModel();

            viewModel.Devices.Add(new SelectListItem() { Text = "MAU110-10", Value = "1" });
            viewModel.Devices.Add(new SelectListItem() { Text = "MAU110-100", Value = "2" });
            viewModel.Devices.Add(new SelectListItem() { Text = "MAU110-101", Value = "3" });
            viewModel.Devices.Add(new SelectListItem() { Text = "MAU110-102", Value = "4" });
            viewModel.Devices.Add(new SelectListItem() { Text = "MAU110-103", Value = "5" });

            viewModel.Users.AddRange(db.Users.ToList());

            return View(viewModel);
        }

        // GET: /Patient/Details/5

        public ActionResult Details(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            User user = db.Users.Find(id);
            if (user == null)
            {
                return HttpNotFound();
            }
            return View(user);
        }

        public ActionResult Create()
        {
            // was ViewBag.DeviceID = new SelectList(db.Devices, "DeviceID", "Name");
            ViewBag.DeviceID = new SelectList(db.Devices, "DeviceID", "Name");
            return View();
        }

        //
        // POST: /Patient/Create

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create([Bind(Include = "UserID,CodeName,UseBriefInstructions")] User user, Device device)
        {
            if (ModelState.IsValid)
            {
                //db.Devices = user.Device.DeviceID;
                db.Users.Add(user);
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            ViewBag.DeviceID = new SelectList(db.Devices, "DeviceID", "Name", user.Device.DeviceID);
            return View(user);
        }

        //
        // GET: /Patient/Edit/5

        public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            User user = db.Users.Find(id);
            if (user == null)
            {
                return HttpNotFound();
            }
            //removed   user.Device.DeviceID
            ViewBag.DeviceID = new SelectList(db.Devices, "DeviceID", "Name");
            return View(user);
        }

        //
        // POST: /Patient/Edit/5

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Edit([Bind(Include = "UserID,CodeName,UseBriefInstructions")] User user)
        {
            if (ModelState.IsValid)
            {
                db.Entry(user).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            ViewBag.DeviceID = new SelectList(db.Devices, "DeviceID", "Name", user.Device.DeviceID);
            return View(user);
        }

        //
        // GET: /Patient/Delete/5

        public ActionResult Delete(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            User user = db.Users.Find(id);
            if (user == null)
            {
                return HttpNotFound();
            }
            return View(user);
            //User user = db.Users.Find(id);
            //if (user == null)
            //{
            //    return HttpNotFound();
            //}
            //return View(user);
        }

        //
        // POST: /Patient/Delete/5

        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public ActionResult DeleteConfirmed(int id)
        {
            User user = db.Users.Find(id);
            db.Users.Remove(user);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

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

我将省略编辑视图以避免进一步的垃圾邮件它基本上包含类似的功能来创建，但是我现在收到多个错误。我已经修好了几个我相信的。对于下拉列表（创建），我收到此错误：

'System.Web.Mvc.HtmlHelper'不包含'DropDownListFor'的定义和最佳扩展方法重载'System.Web.Mvc.Html.SelectExtensions.DropDownListFor（System.Web.Mvc.HtmlHelper），System.Linq.Expressions.Expression＆gt;，System.Collections.Generic.IEnumerable）'有一些无效的参数

对于我正在获得的患者控制器中的viewModel.Devices.Add：

'System.Collections.Generic.ICollection.Add（System.Web.WebPages.Html.SelectListItem）'的最佳重载方法匹配有一些无效的参数

以及：

参数1：无法从'System.Web.Mvc.SelectListItem'转换为'System.Web.WebPages.Html.SelectListItem'

最后，我从AddRange（PatientController）收到错误：

'System.Collections.Generic.IList'不包含'AddRange'的定义，也没有扩展方法'AddRange'接受类型'System.Collections.Generic.IList'的第一个参数'（你错过了使用指令或汇编引用吗？）

* **更新 ***

更改为PatientController.cs

public ActionResult Index(UserDeviceViewModel viewModelDevice)
        {
            var viewModel = new UserDeviceViewModel(); 

            List<UserDeviceViewModel> viewModelList = new List<UserDeviceViewModel>();
            viewModelDevice.Users.AddRange(db.Users.ToList());
            return View(viewModelList);
        }

UserDeviceViewModel.cs

namespace FaceToFaceWebsite.Models
{
    public class UserDeviceViewModel
    {
        public UserDeviceViewModel()
        {
            Device = new Device();
            User = new User();
            Users = new List<User>();
            Devices = new List<SelectListItem>();
        }

        public Device Device { get; set; }
        public Device Name { get; set; }
        public Device DeviceID { get; set; }

        public User UseBriefInstructions { get; set; }
        public User User { get; set; }
        public User UserID { get; set; }
        public User CodeName { get; set; }

        public List<SelectListItem> Devices { get; set; }
        public List<User> Users { get; set; }
    }
}

Index.cshtml（查看）

@model IEnumerable<FaceToFaceWebsite.Models.UserDeviceViewModel>
@*@model IEnumerable<FaceToFace.Model.User>*@

    @{
        ViewBag.Title = "Index";
    }

    <h2>Your Patients</h2>

    @*Showing @Model.Count() users*@

    <p>
        @Html.ActionLink("Add New User", "Create")
    </p>

    <table>
        <tr>
            <th>
                @Html.DisplayNameFor(model => model.UserID)
            </th>
            <th>
                @Html.DisplayNameFor(model => model.CodeName)
            </th>
            <th>
                @*@Html.DisplayNameFor(model => model.Device.Name)*@Device
            </th>
            <th>
                @Html.DisplayNameFor(model => model.Device.DeviceID)
            </th>

        </tr>

        @foreach (var item in Model)
        {
            <tr>
                <td>
                    @Html.DisplayFor(modelItem => item.UserID)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.CodeName)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.Device.Name)
                </td>
                <td>
                    @Html.DisplayFor(modelItem => item.Device.DeviceID)
                </td>
                <td>
                    @Html.ActionLink("Edit", "Edit", new { id = item.UserID }) |
                    @Html.ActionLink("Details", "Details", new { id = item.UserID }) |
                    @Html.ActionLink("Delete", "Delete", new { id = item.UserID })
                </td>
            </tr>
        }

    </table>

我已经让它运行没有错误但是我的原始数据没有来自db的数据显示在索引视图上。它也没有显示我何时创建新用户。

Answer 1

对于DropDownList（您已经声明了User模型）：

@model FaceToFace.Model.User
....
 @Html.DropDownListFor(model => model.Device.DeviceID, (IEnumerable<SelectListItem>)ViewBag.DeviceID)

Answer 2

System.Web.Mvc.HtmlHelper'不包含的定义   'DropDownListFor'和最佳扩展方法重载
  “System.Web.Mvc.Html.SelectExtensions.DropDownListFor（System.Web.Mvc.HtmlHelper，        System.Linq.Expressions.Expression＆gt;，System.Collections.Generic.IEnumerable）'有一些无效的参数

对于上述错误，DeviceID是一个int，它需要是一个字符串，Devices必须是IEnumerable：

@Html.DropDownListFor(model => model.User.Device.DeviceID, Model.Devices)

因此，将公开IList<SelectListItem> Devices { get; set; }更改为public IEnumerable<SelectListItem> Devices { get; set; }

最佳重载方法匹配 'System.Collections.Generic.ICollection.Add（System.Web.WebPages.Html.SelectListItem）' 有一些无效的论点最好的重载方法匹配'System.Collections.Generic.ICollection.Add（System.Web.WebPages.Html.SelectListItem）' 有一些无效的论点

以上两个错误在引用之间存在某种错误匹配，您的控制器有using System.Web.Mvc视图以某种方式拾取System.Web.WebPages.Html，检查是否没有@using System.Web.WebPages.Html观点。

System.Collections.Generic.IList'不包含的定义 'AddRange'并没有扩展方法'AddRange'接受第一个可以找到类型为“System.Collections.Generic.IList”的参数（您是否缺少using指令或程序集引用？）

将您的Users媒体资源改为IEnumerable：

public IEnumerable<User> Users { get; set; }

我的ViewModel导致多个错误

2 个答案: