Question

我获得了code，这有助于我通过下拉菜单为具有管理员状态的用户分配故障单。我无法跟踪控制器中的代码，不知道我是否正确执行了该操作。

错误：

代码我正在尝试转换TicketController

public ActionResult Index()
{
    TicketVM model = new TicketVM();
    ConfigureViewModel(model);
    return View(model);
}

[HttpPost]
public ActionResult Index(TicketVM model)
{
    if (!ModelState.IsValid)
    {
        ConfigureViewModel(model);
        return View(model);
    }
    // Initialise a new data model
    // Set the author based on the current user
    // Set the other properties based on the view model e.g
    Ticket ticket = new Ticket
    {
        // Author = xxx
        Issue = model.Issue,
        IssuedTo = model.IssuedTo 
    };
    // Save the data model and redirect e.g.
    //db.Users.Add(ticket);
    //db.SaveChanges();

    // Cant have more than one view in DotNetFiddle so just return the view
    return View(model);
}

TicketController.cs（我的代码）

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using RecreationalServicesTicketingSystem.Models;
using RecreationalServicesTicketingSystem.DAL;
using RecreationalServicesTicketingSystem.ViewModels;

namespace RecreationalServicesTicketingSystem.Controllers
{
    public class TicketController : Controller
    {
        private IssueContext db = new IssueContext();

        //
        // GET: /Ticket/

        public ActionResult Create()
        {
            TicketVM model = new TicketVM();
            ConfigureViewModel(model);
            return View(model);
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create(TicketVM model)
        {
            if (!ModelState.IsValid)
            {
                ConfigureViewModel(model);
                return View(model);
            }
            Ticket ticket = new Ticket { 

            Issue = model.Issue,
            IssuedTo = model.IssuedTo
        };

            return View(model);

    }
    private void ConfigureViewModel(TicketVM model)
    {


        IEnumerable<User> admins = db.Users.Where(u => u.IsAdministrator).OrderBy(u => u.LastName);
        model.AdministratorList = admins.Select(a => new SelectListItem
        {
            Value = a.UserID.ToString(),
            Text = string.Format("{0} {1}", a.FirstMidName, a.LastName)
        });
    }

    //
    // GET: /Ticket/Details/5

    public ActionResult Details(int id = 0)
        {
            Ticket ticket = db.Tickets.Find(id);
            if (ticket == null)
            {
                return HttpNotFound();
            }
            return View(ticket);
        }

        // POST: /Ticket/Create 


        //
        // GET: /Ticket/Edit/5

        public ActionResult Edit(int id = 0)
        {
            Ticket ticket = db.Tickets.Find(id);
            if (ticket == null)
            {
                return HttpNotFound();
            }
            ViewBag.CategoryID = new SelectList(db.Categories, "CategoryID", "CategoryName", ticket.CategoryID);
            ViewBag.UserID = new SelectList(db.Users, "UserID", "LastName", ticket.UserID);
            return View(ticket);
        }

        //
        // POST: /Ticket/Edit/5

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Edit(TicketVM model)
        {
            if (!ModelState.IsValid)
            {
                ConfigureViewModel(model);
                return View(model);
            }
            Ticket ticket = new Ticket
            {
                // Author = xxx
                Issue = model.Issue,
                IssuedTo = model.IssuedTo
            };
            ViewBag.CategoryID = new SelectList(db.Categories, "CategoryID", "CategoryName", ticket.CategoryID);
            ViewBag.UserID = new SelectList(db.Users, "UserID", "LastName", ticket.UserID);
            return View(ticket);

        }


        //
        // GET: /Ticket/Delete/5

        public ActionResult Delete(int id = 0)
        {
            Ticket ticket = db.Tickets.Find(id);
            if (ticket == null)
            {
                return HttpNotFound();
            }
            return View(ticket);
        }

        //
        // POST: /Ticket/Delete/5

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

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

Ticket.cs

public enum Priority
{
    Low, Med, High
}
public class Ticket
{
    public int? TicketID { get; set; }
    public string Issue { get; set; }
    [DisplayFormat(NullDisplayText = "No Priority")]
    public Priority? Priority { get; set; }
    [ForeignKey("CategoryID")]
    public virtual Category Category { get; set; }
    public int CategoryID { get; set; }
    public int UserID { get; set; }
    [ForeignKey("UserID")]
    public virtual User User { get; set; }

    public int Author { get; set; }
    public int IssuedTo { get; set; }

}

\的ViewModels \ TicketVM.cs

public class TicketVM
{
    public int? UserID { get; set; }
    [Required(ErrorMessage = "Please enter the description")]
    public string Issue { get; set; }
    [Display(Name = "Administrator")]
    [Required(ErrorMessage = "Please select the Administrator")]
    public int IssuedTo { get; set; }
    public IEnumerable<SelectListItem> AdministratorList { get; set; }
    public int CategoryID { get; set; }
    public IEnumerable<SelectListItem> CategoryList { get; set; }
}

\视图\票务\ Create.cshtml

@model RecreationalServicesTicketingSystem.ViewModels.TicketVM

@{
    ViewBag.Title = "Create";
}

<h2>Create</h2>

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

    <fieldset>
        <legend>Ticket</legend>

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

        <div class="editor-label">
            @Html.LabelFor(model => model.CategoryID, "Category")
        </div>
        <div class="editor-field">
            @Html.DropDownList("CategoryID", String.Empty)
            @Html.ValidationMessageFor(model => model.CategoryID)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.UserID, "User")
        </div>
        <div class="editor-field">
            @Html.DropDownList("UserID", String.Empty)
            @Html.ValidationMessageFor(model => model.UserID)
       </div>

            <div class="editor-field">
                @Html.DropDownListFor(m => m.UserID, (IEnumerable<SelectListItem>)ViewBag.AllUsers, "Please select")`
                @Html.ValidationMessageFor(model => model.UserID)
            </div>


        @Html.HiddenFor(m => m.TicketID)
        <div class="form-group">
            @Html.LabelFor(m => m.Issue)
            @Html.TextBoxFor(m => m.Issue, new { @class = "form-control" })
            @Html.ValidationMessageFor(m => m.Issue)
        </div>
        <div class="form-group">
            @Html.LabelFor(m => m.IssuedTo)
            @Html.DropDownListFor(m => m.IssuedTo, Model.AdministratorList, "Please select", new { @class = "form-control" })
            @Html.ValidationMessageFor(m => m.IssuedTo)
        </div>

        <button type="submit" class="btn btn-success submit">Save</button>


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

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

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

Answer 1

我给了你那段代码（来自this DotNetFiddle），但很清楚你还没有理解它。

删除您的Create()方法，并将Index()方法重命名为Create()。

如果你想在Categories的视图中添加一个SelectList，那么添加一个属性（比方说）

public int Category{ get; set; }
public IEnumerable<SelectListItem> CategoryList { get; set; }

到视图模型（使用视图模型时不要使用ViewBag）并将用于填充集合的代码放在ConfigureViewModel()方法中。

Edit方法与Index()方法中当前显示的代码类似，主要区别在于您是否根据ID获取现有数据模型，并将其属性映射到新方法在将视图模型传递给视图之前TicketVM的实例。在POST方法中，您将根据ID再次获取数据模型，并将视图模型属性映射到该模型，然后保存数据模型。

Answer 2

您正在尝试从视图模型中获取这些值，但您没有将该视图模型从控制器传递到视图。如果您使用DropDownListFor，则需要先在控制器中初始化AdministratorList属性，然后将其传递给视图View(model)。如果您使用ViewBag选项，则无需传递视图模型，但需要在视图中使用DropDownList，如下所示：

ViewBag.MyDropdownList = new SelectList(Items, "PropertyOfItemUsedForValue", "PropertyOfItemUsedForText");

然后在您的视图中添加您的下拉列表

@Html.DropDownList("MyDropdownList", null, htmlAttributes: new { @class = "form-control"})

Answer 3

如果您只需要在Enity中绑定下拉列表，那么

https://csharpimp.blogspot.in/2015/12/how-to-bind-dropdown-with-multiple-columns-using-entity-framework.html

带有实体框架的MVC下拉列表分配

3 个答案: