Question

我只是一个新手，我的DropDownList有一个问题：（MVC，ASP.NET）

场景：

在“视图”中，选择下拉菜单后，它将显示值（类别名称）在Controller中，它不会识别（类别名称），而只会识别分配给特定值的ID

问题：

单击保存按钮时，下拉列表的返回值为NULL 然后在CATEGORY表中创建包含EMPTY内容的另一行型号：（供应商）

$ pip3 install --upgrade pip 
 Successfully uninstalled pip-10.0.1
 Successfully installed pip-18.0

型号：（类别）

    public class Supplier
    {
        public int Id { get; set; }
        public string SupplierCode { get; set; }
        public string SupplierName { get; set; }
        public int SupplierContact { get; set; }
        public Category Category { get; set; }
    }

控制器（供应商）

    public class Category
    {
        public int Id { get; set; }
        public string CatName { get; set; }
    }

查看：（供应商）

        public ActionResult New()
        {
            var CategoryMenu = _SBC.Categorys.ToList();
            var NewContent = new SupplierandCategoryViewModel()
            {
               CategoryModel = CategoryMenu,
            };
            return View(NewContent);
        }

        public ActionResult Save(SupplierandCategoryViewModel Supply)
        {   

            var DSupply = new Supplier()
            {
                SupplierName = Supply.SupplierModel.SupplierName,
                SupplierCode = Supply.SupplierModel.SupplierCode,
                SupplierContact = Supply.SupplierModel.SupplierContact,
                Category = Supply.CategoryModel //this part is error; it cannot 
                recognize
            };

            _SBC.Suppliers.Add(DSupply);
            _SBC.SaveChanges();
            return View();
        }

ViewModel：（SupplierandCategoryViewModel）

@model ShoeInformation.ViewModel.SupplierandCategoryViewModel
@{
    ViewBag.Title = "New";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<br />
<br />
<h2>Create New Customer</h2>
<br />
<br />
@using (Html.BeginForm("Save", "Supplier"))
{
    <div class="form-group">
        @Html.LabelFor(x=>x.CategoryModel)
        @Html.DropDownListFor(x => x.CategoryModel, new SelectList(Model.CategoryModel,"Id","CatName"), "Select Supplier Category", new {id="myCat",@class="form-control" })
    </div>

     <div class="form-group">
        @Html.LabelFor(x=>x.SupplierModel.SupplierCode)
        @Html.TextBoxFor(x => x.SupplierModel.SupplierCode, new { @class="form-control"})
    </div>
    <div class="form-group">
        @Html.LabelFor(x=>x.SupplierModel.SupplierName)
        @Html.TextBoxFor(x => x.SupplierModel.SupplierName, new { @class="form-control"})
    </div>
    <div class="form-group">
        @Html.LabelFor(x=>x.SupplierModel.SupplierContact)
        @Html.TextBoxFor(x => x.SupplierModel.SupplierContact, new { @class="form-control"})
    </div>

}

我想保存类别的ID，但是在view（Index）中它必须显示ID的值而不是ID本身

感谢您的回复！

Answer 1

1）向您的SelectedCategory添加一个SupplierandCategoryViewModel属性

public class SupplierandCategoryViewModel
{
    public IEnumerable<Category> CategoryModel { get; set; }
    public Supplier SupplierModel { get; set; }
    public int SelectedCategory { get; set; }     <== Add this property
}

2）为Id

提供合适的名称

public class Category
{
    public int CategoryId { get; set; }    <== Change the name
    public string CatName { get; set; }
}

3）将此CategoryId引用到您的Supplier模型中

public class Supplier
{
    public int Id { get; set; }
    public string SupplierCode { get; set; }
    public string SupplierName { get; set; }
    public int SupplierContact { get; set; }
    public int CategoryId { get; set; }        <== Reference to this property
    public Category Category { get; set; }
}

4）像修改您的DropDownListFor

@Html.DropDownListFor(x => x.SelectedCategory, new SelectList(Model.CategoryModel, "CategoryId", "CatName"), "Select Supplier Category", new { id = "myCat", @class = "form-control" })

5）最后，您的Save操作方法就像

public ActionResult Save(SupplierandCategoryViewModel Supply)
{

    var DSupply = new Supplier()
    {
        SupplierName = Supply.SupplierModel.SupplierName,
        SupplierCode = Supply.SupplierModel.SupplierCode,
        SupplierContact = Supply.SupplierModel.SupplierContact,
        CategoryId = Supply.SelectedCategory                     <==Note here I assigned SelectedCategory to model's CategoryId
    };

    _SBC.Suppliers.Add(DSupply);
    _SBC.SaveChanges();
    return View();
}

DropDownList的测试数据：

var CategoryMenu = new List<Category> { new Category { CategoryId = 1, CatName = "Abc" }, new Category { CategoryId = 2, CatName = "Pqr" } };

输出：

如何将选定的ID从DropDownListFor传递到ASP.NET MVC中的控制器

1 个答案: