如何填充数据列表框，并保存到数据库中的ASP.NET mvc5 [英] how to populate data to listbox and save to database in asp .net mvc5

问题描述

我有2个模型类。一个是Book.cs，另一个是Cateogry.cs。图书和类别有许多一对多的关系。所以，我创建了另一个视图模型BookCategory.cs。我想创建内部BookController.cs的类别列表框和创建书/ Edit.cshtml页面应该有列表框为那里的一本书可以与类别的多项选择创建/保存/编辑数据库一起类别。这里是我的模型codeS。默认BookController的给我只为类别的DropDownList。怎样才可以有列表框呢？请给我任何suggesion。我刚进入MVC仅为2周。谢谢了很多。

Book.cs

 公共类图书
{
    公众诠释BOOKID {搞定;组; }    公共字符串BOOKNAME {搞定;组; }    公共虚拟的ICollection＆LT;类别及GT;分类{搞定;组; }
 

Category.cs

 公众诠释的CategoryId {搞定;组; }    公共字符串类别名称{搞定;组; }    公共虚拟的ICollection＆LT;图书＆GT;图书{搞定;组; }
 

我的视图模型为BookCategoryVM.cs

 公共类BookCategoryVM
{
    公众诠释的CategoryId {搞定;组; }
    公共字符串类别名称{搞定;组; }
    公共BOOL IsSelected {搞定;组; }    公共IEnumerable的＆LT;图书＆GT;图书{搞定;组; }
    公共IEnumerable的＆LT;类别及GT;分类{搞定;组; }
}
 

解决方案

您创建或编辑的书需要包括对所选类别的属性视图模型

 公共类BookVM
{
  公众诠释ID {搞定;组; } //只需要编辑现有图书
  [需要]
  公共字符串名称{;组; }
  [显示（名称=分类）]
  [必需（的ErrorMessage =请至少选择一个类别）]
  公众诠释[] {SelectedCategories获得;组; }
  公众的SelectList所属分类{搞定;组; }
}
 

查看

  @ Html.LabelFor（M = GT; m.SelectedCategories）
@ Html.ListBoxFor（M = GT; m.SelectedCategories，Model.CategoryList）
@ Html.ValidationMessageFor（M = GT; m.SelectedCategories）
 

控制器

 公众的ActionResult的Create（）
{
  BookVM模式=新BookVM（）;
  IEnumerable的＆LT;类别及GT;类别= db.Categories; //修改以满足您的要求
  model.CategoryList =新的SelectList（类别的CategoryId，类别名称）
  返回查看（模型）;
}公众的ActionResult创建（BookVM模型）
{
  // model.SelectedCategories将包含在列表框中选择的每个类别的ID
}
 

I have 2 model class. One is Book.cs and the other is Cateogry.cs. Book and Category has many-to-many relationship. So, I created another viewmodel BookCategory.cs. I want to create a listbox for Category inside BookController.cs and Create/Edit.cshtml pages of Book should have listbox for Category where a book can be created/saved/edit to database together with multiselection of category. Here is my model codes. Default Bookcontroller gives me only dropdownlist for category. How can I have listbox instead? Please give me any suggesion. I just get into MVC for 2 weeks only. Thank a lot.

Book.cs

 public class Book
{
    public int BookId{ get; set; }

    public string BookName { get; set; }

    public virtual ICollection<Category> Categories { get; set; }

Category.cs

    public int CategoryId { get; set; }

    public string CategoryName { get; set; }

    public virtual ICollection<Book> Books { get; set; }

My ViewModel for BookCategoryVM.cs

   public class BookCategoryVM
{
    public int CategoryId { get; set; }
    public string CategoryName { get; set; }
    public bool IsSelected { get; set; }

    public IEnumerable<Book> Books { get; set; }
    public IEnumerable<Category> Categories { get; set; }
}

解决方案

Your view model for creating or editing a book need to include a property for the selected categories

public class BookVM
{
  public int ID { get; set; } // only required for editing existing book
  [Required]
  public string Name { get; set; }
  [Display(Name = "Categories")]
  [Required(ErrorMessage = "Please select at least one category")]
  public int[] SelectedCategories { get; set; }
  public SelectList CategoryList { get; set; }
}

View

@Html.LabelFor(m => m.SelectedCategories)
@Html.ListBoxFor(m => m.SelectedCategories, Model.CategoryList)
@Html.ValidationMessageFor(m => m.SelectedCategories)

Controller

public ActionResult Create()
{
  BookVM model = new BookVM();
  IEnumerable<Category> categories = db.Categories; // modify to suit your requirements
  model.CategoryList = new SelectList(categories, "CategoryId", "CategoryName")
  return View(model);
}

public ActionResult Create(BookVM model)
{
  // model.SelectedCategories will contain the ID of each category selected in the listbox
}

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