Question

我正在尝试为book（id为1）创建编辑表单，我希望选择列表选择从数据库中检索的现有作者。 id为1的那本书的作者身份为1，但HTML并未显示该书的ID为1的选定作者。

我觉得这个论点有问题 ViewData [“SelectedAuthors”]为IEnumerable 在MultiSelectList函数在Book.ascx源文件

另一个问题是，如何使用MultiSelectList将“first_name”和“last_name”结合起来进行文本显示？我只能选择“first_name”

StoreManagerViewModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using BookStore.Models;

namespace BookStore.ViewModels
{
    public class StoreManagerViewModel
    {
        public book Book { get; set; }
        public List<author> Authors { get; set; }
        public List<category> Categories { get; set; }
        public List<int> SelectedAuthors { get; set; }
    }
}

StoreManagerController.cs

using System;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using BookStore.Models;
using BookStore.ViewModels;

namespace BookStore.Controllers
{
    public class StoreManagerController : Controller
    {
        BookStoreEntities storeDB = new BookStoreEntities();

        //
        // GET: /StoreManager/Edit/5

        public ActionResult Edit(int id)
        {
            var viewModel = new StoreManagerViewModel
            {
                Book = storeDB.books.Single(a => a.book_id == id),
                Categories = storeDB.categories.ToList(),
                Authors = storeDB.authors.ToList(),
                SelectedAuthors = (from a in storeDB.books.Single(b => b.book_id == id).authors
                                    select a.author_id
                                  ).ToList()
            };

            //I have debug and have seen that the SelectedAuthors list has one author_id as 1

            return View(viewModel);
        }

    }
}

StoreManagerController的“edit”方法的Book.ascx（部分视图）

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<BookStore.Models.book>" %>

    <% using (Html.BeginForm()) {%>
        <%: Html.ValidationSummary(true) %>


            <div class="editor-label">
                <%: Html.LabelFor(model => model.authors) %>
            </div>
            <div class="editor-field">
                <%: Html.ListBox("author_id", new MultiSelectList(ViewData["authors"] as IEnumerable, "author_id", "first_name", ViewData["SelectedAuthors"] as IEnumerable))%>
            </div>

    <% } %>

Book.ascx局部视图的HTML结果

<select id="Book_author_id" multiple="multiple" name="Book.author_id">
<option value="1">Bikkhu</option>
<option value="2">Buddha</option>
<option value="3">William</option>
<option value="4">Anthony</option>
</select>

Answer 1

您正在使用需要绑定到作为集合的模型属性的多选列表。在您的情况下，您绑定到"author_id"，它只能包含一个选定的项ID。此外，您在部分中使用ViewData["authors"]和ViewData["SelectedAuthors"]，但在控制器操作中，不清楚这些属性是如何填充的。

Answer 2

现在已经解决了，我没有在“edit.aspx”视图中将“SelectedAuthors”提供给“Book.ascx”的局部视图

<%: Html.EditorFor(model => model.Book,
    new { Authors = Model.Authors, Categories = Model.Categories, SelectedAuthors = Model.SelectedAuthors }) %>

在ASP.NET MVC中使用MultiSelectList

2 个答案: