ASP.NET MVC Viewmodel 编辑 returns 空字段（项目未通过 ID 标识）

Question

我之前得到了一些帮助 here 但现在 "Edit" 出现了一些问题。目前卡在HttpGet，HttpPost还没来

简而言之，每当我单击要编辑的现有项目时，它 returns 一个空表单 as seen here 而不是预期值。（您可能认为这是因为我对“创建”和“编辑”使用了完全相同的视图，但不幸的是，这不是，即使我过去常常将它们分开，也有相同的结果。）

Town.cs

using System.Collections.Generic;

namespace City.Models
{
    public class Town
    {
        public Town()
        {
            Streets = new List<Street>();
        }
        public int TownId { get; set; }
        public string TownName { get; set; }
        public virtual ICollection<Street> Streets { get; set; }
    }
}

Street.cs

using System.Collections.Generic;

namespace City.Models
{
    public class Street
    {
        public Street()
        {
            Houses = new List<House>();
        }
        public int StreetId { get; set; }
        public string StreetName { get; set; }
        public virtual ICollection<House> Houses { get; set; }
    }
}

House.cs

using System.Collections.Generic;

namespace City.Models
{
    public class House
    {
        public House()
        {
            Floors = new List<Floor>();
        }
        public int HouseId { get; set; }
        public string HouseName { get; set; }
        public ICollection<Floor> Floors { get; set; }
    }
}

Floor.cs

using System.Collections.Generic;

namespace City.Models
{
    public class Floor
    {
        public Floor()
        {
            FireExtinguishers = new List<FireExtinguisher>();
        }
        public int FloorId { get; set; }
        public int FloorNumber { get; set; }
        public virtual ICollection<FireExtinguisher> FireExtinguishers { get; set; }
    }
}

FireExtinguisher.cs

using System.ComponentModel;

namespace City.Models
{
    public class FireExtinguisher
    {
        public int FireExtinguisherId { get; set; }
        [DisplayName("Fire Extinguisher")]
        public string FireExtinguisherName { get; set; }
        public int FloorId { get; set; }
        public int HouseId { get; set; }
        public int StreetId { get; set; }
        public int TownId { get; set; }
        public Floor Floor { get; set; }
        public House House { get; set; }
        public Street Street { get; set; }
        public Town Town { get; set; }
    }
}

MyViewModel.cs

using System.Collections.Generic;

namespace City.Models
{
    public class MyViewModel
    {
        public IEnumerable<Town> TownId { get; set; }
        public IEnumerable<Street> StreetId { get; set; }
        public IEnumerable<House> HouseId { get; set; }
        public IEnumerable<Floor> FloorId { get; set; }
        public FireExtinguisher FireExtinguisher { get; set; }
        public string FireExtinguisherName { get; set; }
    }
}

Create/Edit 查看

@model City.Models.MyViewModel

<h2>Add new or edit existing FE</h2>

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

    <div class="form-horizontal">
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })

        <div class="col-md-12">

            <div class="form-group">
                @Html.LabelFor(model => model.TownId, "Town", new { @class = "control-label col-md-2" })
                <div class="col-md-10">
                    @Html.DropDownListFor(model => model.TownId, new SelectList(Model.TownId, "TownId", "TownName"), "Choose Town", new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.TownId, "", new { @class = "text-danger" })
                </div>
            </div>

            <div class="form-group">
                @Html.LabelFor(model => model.StreetId, "Street", new { @class = "control-label col-md-2" })
                <div class="col-md-10">
                    @Html.DropDownListFor(model => model.StreetId, new SelectList(Model.StreetId, "StreetId", "StreetName"), "Choose Street", new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.StreetId, "", new { @class = "text-danger" })
                </div>
            </div>

            <div class="form-group">
                @Html.LabelFor(model => model.HouseId, "House", new { @class = "control-label col-md-2" })
                <div class="col-md-10">
                    @Html.DropDownListFor(model => model.HouseId, new SelectList(Model.HouseId, "HouseId", "HouseName"), "Choose House", new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.HouseId, "", new { @class = "text-danger" })
                </div>
            </div>

            <div class="form-group">
                @Html.LabelFor(model => model.FloorId, "Floor", new { @class = "control-label col-md-2" })
                <div class="col-md-10">
                    @Html.DropDownListFor(model => model.FloorId, new SelectList(Model.FloorId, "FloorId", "FloorNumber"), "Choose Floor", new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.FloorId, "", new { @class = "text-danger" })
                </div>
            </div>

            <div class="form-group">
                @Html.LabelFor(model => model.FireExtinguisherName, "Fire Extinguisher", new { @class = "control-label col-md-2" })
                <div class="col-md-10">
                    @Html.TextBoxFor(model => model.FireExtinguisherName, new { @class = "form-control", Value = "" })
                    @Html.ValidationMessageFor(model => model.FireExtinguisherName, "", new { @class = "text-danger" })
                </div>
            </div>

        </div>


        <div>
            <div>
                <input type="submit" value="Do it" class="btn btn-default" />
            </div>
        </div>
    </div>

}

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

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

Homecontroller.cs

using System;
using System.Linq;
using System.Net;
using System.Web.Mvc;
using City.Models;

namespace City.Controllers
{
    public class HomeController : Controller
    {
        private ApplicationDbContext db;
        private MyViewModel viewModel;

        public HomeController()
        {
            db = new ApplicationDbContext();

            var town = db.Towns.ToList();
            var street = db.Streets.ToList();
            var house = db.Houses.ToList();
            var floor = db.Floors.ToList();

            viewModel = new MyViewModel()
            {
                TownId = town,
                StreetId = street,
                HouseId = house,
                FloorId = floor
            };
        }
        public ActionResult Index()
        {
            return View(db.FireExtinguishers.ToList());
        }

        [HttpGet]
        public ActionResult Create()
        {
            return View(viewModel);
        }

        [HttpPost]
        public ActionResult Create(FireExtinguisher fe)
        {
            if (ModelState.IsValid)
            {
                db.FireExtinguishers.Add(fe);
                db.SaveChanges();

                return RedirectToAction("Index");
            }
            return View(viewModel);
        }

        [HttpGet]
        public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            var fe = db.FireExtinguishers.Find(id);

            var town = db.Towns.ToList();
            var street = db.Streets.ToList();
            var house = db.Houses.ToList();
            var floor = db.Floors.ToList();

            viewModel = new MyViewModel()
            {
                FireExtinguisher = fe,

                TownId = town,
                StreetId = street,
                HouseId = house,
                FloorId = floor
            };
            return View("Create", viewModel);
        }

        [HttpPost]
        public ActionResult Edit()
        {
            throw new NotImplementedException();
        }
    }
}

任何帮助将不胜感激，谢谢

Answer 1

就我个人而言，我喜欢使用 View- 和 Post-Models 作为一个明确的声明，发送到 View (ViewModel) 的内容以及通过 Post 发回的内容。作为命名约定，模型名称 class 采用控制器名称和操作名称。

我从 Post模型开始，你的情况就是这样

public class HomeEditPostModel
{
    [Required]
    [MaxLength(50)]
    public string Name { get; set; }
    [Required]
    public int TownId { get; set; }
    [Required]
    public int StreetId { get; set; }
    [Required]
    public int HouseId { get; set; }
    [Required]
    public int FloorId { get; set; }
}

现在对于视图，我们需要一些下拉字段集合，我们可以从select

public class SelectionItem<TKey>
{
    public TKey Key { get; set; }
    public string DisplayName { get; set; }
}

public class HomeEditViewModel : HomeEditPostModel
{
    public IEnumerable<SelectionItem<int>> Town { get; set; }
    public IEnumerable<SelectionItem<int>> Street { get; set; }
    public IEnumerable<SelectionItem<int>> House { get; set; }
    public IEnumerable<SelectionItem<int>> Floor { get; set; }
}

现在的景色

@model WebApplication6.Models.HomeEditViewModel

@{
    ViewBag.Title = "Edit";
}

<h2>Edit</h2>


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

    <div class="form-horizontal">
        <h4>HomeEditSubmitModel</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.Name, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Name, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Name, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.TownId, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownListFor(model => model.TownId, new SelectList(Model.Town, "Key", "DisplayName"), "Choose Town", new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.TownId, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.StreetId, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownListFor(model => model.StreetId, new SelectList(Model.Street, "Key", "DisplayName"), "Choose Street", new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.StreetId, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.HouseId, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownListFor(model => model.HouseId, new SelectList(Model.House, "Key", "DisplayName"), "Choose House", new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.HouseId, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.FloorId, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownListFor(model => model.FloorId, new SelectList(Model.Floor, "Key", "DisplayName"), "Choose Floor", new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.FloorId, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </div>
    </div>
}

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

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

最后是控制器（仅相关部分）

public class HomeController : Controller
{
    [HttpGet]
    public ActionResult Edit(int id)
    {
        // just some fake data for demonstration
        var model = new HomeEditViewModel
        {
            Name = "Name",
            Floor = Enumerable.Range(1, 10).Select(e => new SelectionItem<int> { Key = e, DisplayName = $"Floor {e}" }),
            Street = Enumerable.Range(1, 10).Select(e => new SelectionItem<int> { Key = e, DisplayName = $"Street {e}" }),
            House = Enumerable.Range(1, 10).Select(e => new SelectionItem<int> { Key = e, DisplayName = $"House {e}" }),
            Town = Enumerable.Range(1, 10).Select(e => new SelectionItem<int> { Key = e, DisplayName = $"Town {e}" }),

            FloorId = 3,
            StreetId = 4,
            HouseId = 5,
            TownId = 6,
        };
        return View(model);
    }

    [HttpPost]
    public ActionResult Edit(int id, HomeEditPostModel model)
    {
        // needs to save the data here

        return RedirectToAction(nameof(Index));
    }
}

ASP.NET MVC Viewmodel 编辑 returns 空字段（项目未通过 ID 标识）

ASP.NET MVC Viewmodel Edit returns empty fields (item is not identified by id)

c#

asp.net

edit

viewmodel