如何将ID od下拉保存到数据库中 [英] How to save the ID od dropdown to database

问题描述

大家好，我只是个新手，我的DropDownList有问题：（MVC，ASP.NET）



场景：

>在视图中，当选择下拉列表时，它会显示值（类别名称）

>在Controller中，而不是（类别名称）它将只识别指定ID到特定值



问题：

>当它点击按钮保存时，下拉列表中的返回值为NULL

>然后在CATEGORY表中创建另一行，其中包含EMPTY内容

型号:(供应商）

Hi Everyone, I'm just a newbie and I have a problem to my DropDownList:(MVC, ASP.NET)

Scenario:
> In View, when the dropdown is selected it display the value (Category Name)
> In Controller, instead of (category name) it will recognize only the assigned ID to the specific value

Problem:
> when it click the button save, the return value from dropdownlist is NULL
> then in the CATEGORY table it create another row with an EMPTY content
Model: (Supplier)

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; }
   }

型号:(类别）

Model: (Category)

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

控制器（供应商）

Controller (Supplier)

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();
        }

查看:(供应商）

View: (Supplier)

@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>
    
}

ViewModel：（

ViewModel: (

SupplierandCategoryViewModel

）

)

public class SupplierandCategoryViewModel
    {
        public IEnumerable<Category> CategoryModel { get; set; }
        public Supplier SupplierModel { get; set; }
    }

我想保存类别的ID但在视图（索引）中它必须显示ID的值不是身份证本身



感谢您的回复!!



我的尝试：



我尝试使用Supply的模型，但问题是它无法列出类别的内容

I want to save the ID of category but in view(Index) it must display the value of ID not the ID itself

Thanks for your Response!!

What I have tried:

I try to used the model of Supply but the problem it cannot list the content of category

推荐答案

你好像很困惑。



SupplierandCategoryViewModel

• CategoryModel 是类别列表;
• SupplierModel.Category 是选定的类别;

You seem to be getting very confused.

SupplierandCategoryViewModel

• CategoryModel is the list of categories;
• SupplierModel.Category is the selected category;

@Html.DropDownListFor(x => x.CategoryModel, ...

您正在尝试渲染下拉列表以选择整个类别列表。您应该选择单个而不是类别。



控制器：

You are trying to render a drop-down list to select the entire list of categories. You should be selecting the single category instead.

Controller:

public ActionResult Save(SupplierandCategoryViewModel Supply)
{
    ...
    Category = Supply.CategoryModel

您正试图存储列表类别在一个只能存储单个类别的房产。





从简化开始您的视图模型：

You are trying to store the list of categories in a property which can only store a single category.


Start by simplifying your view model:

public class SupplierandCategoryViewModel
{
    // The properties which will be edited:
    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; }
    
    // The data for any drop-down lists:
    public IEnumerable<Category> AllCategories { get; set; }
}

然后更新你的行动：

public ActionResult New()
{
    var viewModel = new SupplierandCategoryViewModel
    {
        AllCategories = _SBC.Categorys.ToList(),
    };
    
    return View(viewModel);
}

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Save(SupplierandCategoryViewModel viewModel)
{
    Supplier supplier;
    if (viewModel.Id == 0)
    {
        supplier = new Supplier();
        _SBC.Suppliers.Add(supplier);
    }
    else
    {
        supplier = _SBC.Suppliers.Single(s => s.Id == viewModel.Id);
    }
    
    supplier.SupplierName = viewModel.SupplierName;
    supplier.SupplierCode = viewModel.SupplierCode;
    supplier.SupplierContact = viewModel.SupplierContact;
    supplier.Category = _SBC.Categorys.Single(c => c.Id == viewModel.CategoryId);
    
    _SBC.SaveChanges();
    return View();
}

然后您的表单变为：

...
@using (Html.BeginForm("Save", "Supplier"))
{
    @Html.AntiForgeryToken()
    
    <div class="form-group">
        @Html.LabelFor(x => x.CategoryId)
        @Html.DropDownListFor(x => x.CategoryId, new SelectList(Model.AllCategories, "Id", "CatName"), "Select Supplier Category", new { id="myCat", @class="form-control" })
    </div>
    
     <div class="form-group">
        @Html.LabelFor(x => x.SupplierCode)
        @Html.TextBoxFor(x => x.SupplierCode, new { @class="form-control" })
    </div>
    <div class="form-group">
        @Html.LabelFor(x => x.SupplierName)
        @Html.TextBoxFor(x => x.SupplierName, new { @class="form-control" })
    </div>
    <div class="form-group">
        @Html.LabelFor(x => x.SupplierContact)
        @Html.TextBoxFor(x => x.SupplierContact, new { @class="form-control" })
    </div>
    
    <p><button type="submit" class="btn btn-primary">Save</button></p>
}

您可能希望为视图模型添加一些验证属性：

使用数据注释验证器进行验证（ C＃）| Microsoft Docs [ ^ ]

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