Question

我似乎在下载列表中填充和绑定MVC时遇到了一些问题。我有一个简单的例子，它有一个带有流派项目的电影列表，下面填充了一个下拉列表。

我通过一个选择列表，其中包含要填充下拉列表的项目，但在发布后期操作时似乎遇到了问题。

问题似乎是：返回的ViewModel似乎在Post动作上将GenreList返回为null。似乎没有设置类型，以便在编辑后 - 正确填充下拉列表。

我似乎无法找到一个好的答案，并且已经尝试了很多例子，但似乎是围成一圈。想尝试让这个最基本的下拉列表编辑示例正常工作，这样我就可以看到它应该如何实现。

模型类

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Web;

namespace Test.Models
{
public class Genre
{
    [Key]
    public int Id { get; set; }
    public string Description { get; set; }
}


public class Movie
{
    [Key]
    public int MovieID { get; set; }

    public string Name { get; set; }


    public Genre MovieGenre { get; set; }
}

public class MovieViewModel
{
    public Movie MovieItem { get; set; }
    public SelectList GenreList{ get; set; }

}
}

控制器代码

namespace Test.Controllers
{
    public class MoviesController : Controller
    {

        private DataContext _dc = new DataContext();

        // GET: Movies
        public ActionResult Index()
        {
            var x = from m in _dc.Movies
                    select m;

            return View(x.ToList());
        }

        // GET: Movies/Edit/5
        public ActionResult Edit(int id)
        {

            var x = from m in _dc.Movies
                    where m.MovieID == id
                    select m;

            var l = from m in _dc.Genres
                    select m;

            var y = new MovieViewModel
            {
                GenreList = new SelectList(l.ToList(), "ID", "Description"),
                MovieItem = x.FirstOrDefault()
            };

            return View(y);
        }

        // POST: Movies/Edit/5
        [HttpPost]
        public ActionResult Edit(int id, MovieViewModel m)
        {
            // PROBLEM: GenreList in model is now not populate for return

            if (ModelState.IsValid)
            {

                var movie = _dc.Movies.Find(id);
                movie.Name = m.MovieItem.Name;
                movie.MovieGenre = m.MovieItem.MovieGenre;
                // PROBLEM: The MovieGenre does not appear to be saved correctly 
                //          when you make the edit and go back to that record after saving
                //          the dropdown is not populated.
                _dc.SaveChanges();
                return RedirectToAction("Index", "Movies");
            }



            return View(m);
        }


    }
}

Razor查看代码

@model Test.Models.MovieViewModel

@{
    ViewBag.Title = "Edit";
}

<h2>Edit</h2>


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

    <div class="form-horizontal">
        <h4>Movie</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        @Html.HiddenFor(model => model.MovieItem.MovieID)

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

        <div class="form-group">
            <div>
                @Html.LabelFor(m => m.GenreList, "Genre:")
                @Html.DropDownListFor(m => m.MovieItem.MovieGenre.Id, (IEnumerable<SelectListItem>) Model.GenreList)


            </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>

在MVC5中实现绑定下拉列表 - Post操作返回空值

0 个答案: