如何在 MVC 中的 Controller 中获取下拉值

Question

我使用递归函数使用字符串列表绑定下拉列表
我的下拉菜单具有类似的价值 家 首页>> 厨房 首页>> 厨房>> ABC

我想在数据库中使用相同的下拉值 ABC

这是我的查看代码

@{
    ViewBag.Title = "Createnewproduct";
}
<h2>
    Create new product</h2>
<div>
    @using (Html.BeginForm("Createnewproduct", "ProductAdmin", FormMethod.Post, new { id = "sendFileForm", enctype = "multipart/form-data" }))
    {
        <table>
            <tr>
                <td>
                    Category
                </td>
                <td>
                    @Html.DropDownList("Test", new SelectList(ViewBag.ListOfDisciplines, Model))
                </td>
            </tr>
            <tr>
                <td>
                    Product Name
                </td>
                <td>
                    <input type="text" name="ProductName">
                </td>
            </tr>
            <tr>
                <td>
                    Product Description
                </td>
                <td>
                    <input type="text" name="ProductDescription">
                </td>
            </tr>
            <tr>
                <td>
                    Product long Description
                </td>
                <td>
                    <input type="text" name=" ProductlongDescription">
                </td>
            </tr>
            <tr>
                <td>
                    UPC
                </td>
                <td>
                    <input type="text" name="UPC">
                </td>
            </tr>
            <tr>
                <td>
                    SKU
                </td>
                <td>
                    <input type="text" name="SKU">
                </td>
            </tr>
            <tr>
                <td>
                    Stock
                </td>
                <td>
                    <input type="text" name="Stock">
                </td>
            </tr>
            <tr>
                <td>
                    Weight
                </td>
                <td>
                    <input type="text" name="Weight">
                </td>
            </tr>
            <tr>
                <td>
                    Height
                </td>
                <td>
                    <input type="text" name="Height">
                </td>
            </tr>
            <tr>
                <td>
                    Image URL
                </td>
                <td>
                    <input type="file" name="file" id="file" style="width: 100%;" id="Imageupload" />
                </td>
            </tr>
            <tr>
                <td rowspan="2">
                    <input type="submit" value="Save" />
                </td>
            </tr>
        </table>
    }
</div>

和我的控制器这样

[AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Createnewproduct(FormCollection form)
        {

        }

当我看到我的 FormCollection 值时，我没有找到下拉值，所有其他值在 FormCollection 中正确找到

请帮助我在这段代码中哪里出错了

---

 public ActionResult Createnewproduct()
    {
        List<Category> categorylist = _Listofcategory();
        var parentcate = categorylist.Where(c => c.ParentCategoryId == 1).ToList();
        List<String> categoryList = new List<string>();
        string prefix = ">>";
        foreach (var item in parentcate)
        {
            prefix = item.CategoryName;
            Setchild(prefix, item, categorylist, categoryList);


        }

        ViewBag.ListOfDisciplines = categoryList;
        return View();
    }


    private void Setchild(string prefix, Category model, List<Category> listcategory, List<string> catStrings)
    {
        var childs = listcategory.Where(x => x.ParentCategoryId == model.CategoryId).ToList();

        catStrings.Add(prefix);
        if (childs.Count > 0)
        {

            foreach (var child in childs)
            {
                catStrings.Add(prefix + ">>" + child.CategoryName);
                var subchild = listcategory.Where(c => c.ParentCategoryId == child.CategoryId).ToList();
                if (subchild.Count > 0)
                {
                    foreach (var subsubchild in subchild)
                    {
                        catStrings.Add(prefix + ">>" + child.CategoryName + ">>" + subsubchild.CategoryName);

                        var subsubsubchild = listcategory.Where(c => c.ParentCategoryId == subsubchild.CategoryId).ToList();
                        if (subsubsubchild.Count > 0)
                        {
                            foreach (var subsubsubsubchild in subsubsubchild)
                            {
                                catStrings.Add(prefix + ">>" + child.CategoryName + ">>" + subsubchild.CategoryName + ">>" + subsubsubsubchild.CategoryName);
                            }
                        }
                    }
                }


            }

        }

    }

这是我的类别列表如何在视图模型中使用。

请告诉我

Answer 1

您也可以将下面提到的示例代码用于您的场景。这里我使用了 ViewModel。

领域模型：

 public class Product
    {
        public Product() { Id = Guid.NewGuid(); Created = DateTime.Now; }
        public Guid Id { get; set; }
        public string ProductName { get; set; }
        
        public virtual ProductCategory ProductCategory { get; set; }
    }

 public class ProductCategory
    {
        public int Id { get; set; }
        public string CategoryName { get; set; }

        public virtual ICollection<Product> Products { get; set; }
    }

查看模型：

public class ProductViewModel
    {
        public Guid Id { get; set; }

        [Required(ErrorMessage = "required")]
        public string ProductName { get; set; }
        
        public int SelectedValue { get; set; }
    
        public virtual ProductCategory ProductCategory { get; set; }

        [DisplayName("Product Category")]
        public virtual ICollection<ProductCategory> ProductCategories { get; set; }
    }

动作方法：

 [HttpGet]
        public ActionResult AddProduct() //generate view with categories for enter product data
        {
            //for get product categories from database
            var prodcutCategories = Repository.GetAllProductCategories();

            //for initialize viewmodel
            var productViewModel = new ProductViewModel();
            
            //assign values for viewmodel
            productViewModel.ProductCategories = prodcutCategories;

            //send viewmodel into UI (View)
            return View("AddProduct", productViewModel);
        }

        [HttpPost]
        public ActionResult AddProduct(ProductViewModel productViewModel) //save entered data
        {
            //get product category for selected drop down list value
            var prodcutCategory = Repository.GetProductCategory(productViewModel.SelectedValue);
            
            //for get all product categories
       var prodcutCategories = Repository.GetAllProductCategories();

            //for fill the drop down list when validation fails 
             productViewModel.ProductCategories = prodcutCategories;

            //for initialize Product domain model
            var productObj = new Product
                                     {
                                         ProductName = productViewModel.ProductName,
                                         ProductCategory = prodcutCategory,
                                     };

            if (ModelState.IsValid) //check for any validation errors
            {
                //save recived data into database
                Repository.AddProduct(productObj);
                return RedirectToAction("AddProduct");
            }
            else
            {
                //when validation failed return viewmodel back to UI (View) 
                return View(productViewModel);
            }
        }

查看：

@model YourProject.ViewModels.ProductViewModel        //set your viewmodel here

 <div class="boxedForm">
  
@using (Html.BeginAbsoluteRouteForm("add", new { action = "AddProduct"},FormMethod.Post }))
         {
             <ul>
                     <li style="width: 370px">
                           @Html.LabelFor(m => m.ProductCategories)
   @Html.DropDownListFor(m => m.SelectedValue,new SelectList(Model.ProductCategories, "Id",
                                             "CategoryName"),"-Please select a category -")
                           @Html.ValidationMessageFor(m => m.ProductCategory.Id)
                    </li>
                    <li style="width: 370px">
                  @Html.CompleteEditorFor(m => m.ProductName, labelOverride: "Product Name")
                  @Html.ValidationMessageFor(m => m.ProductName) 
                    </li>
            </ul>
                    <div class="action">
                        <button class="actionButton" type="submit">
                            <span>Save</span></button>
                    </div>
         }
   </div>

最终输出

Answer 2

假设您的 ViewBag.ListOfDisciplines 是 List<Discipline> 并且您的 Discipline 课程是：

public class Discipline {
     public int Id { get; set; }
     public string Name { get; set; }
}

如果你有一个字符串列表，你可以在控制器端将它转换成一个匿名数组

ViewBag.ListOfDIsciplines = from d in ListDisciplines select new { Id = d, Name = d };

在你看来你应该使用

@Html.DropDownList("Test", new SelectList(ViewBag.ListOfDisciplines, "Id", "Name"), "-- Select here --")