如何從ASP.Net MVC中的下拉菜單中讀取數據3

Question

步驟1：

我正在使用下拉菜單來顯示公司位置。該列表來自位置表。

步驟2：

當用戶註冊時，下拉列表將顯示有問題的地點。

當用戶選擇印度時，此值（位置名稱）應存儲在用戶登錄表中。

如何從ASP.Net MVC 3的下拉菜單中讀取值？

Answer 1

這取決於如果傳遞的FormCollection那麼簡單，你可以通過這個

public ActionResult MyAction (FormCollection form) 
    { 
     string value = form["DropDownListName"]; 
    } 

訪問它的值，或者您可以訪問它通過

string value = Request.Form["DropDownListName"]; 

Answer 2

創建你如何讓你的表單值ViewModel for your form

public class CompanyViewModel 
{ 
    public int CompanyId { set;get;} 
    // Other properties of Company 
    public int SelectedLocationId { set;get;} 
    public IEnumerable<Location> Locations { set;get;} 
} 

假設你有這樣的位置類

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

在寄存器（HTTPGET）動作方法，返回一個CompanyViewModel對象從數據庫填充查看

public ActionReuslt Register() 
{ 
    CompanyViewModel model=new CompanyViewModel(); 
    model.Locations =myRepositary.GetAllLocations(); 
    return View(model); 
} 

假設GetAllLocations收益從您repositary定位對象的列表位置。

而且在註冊查看這是強類型到CompanyViewModel

@model CompanyViewModel 
@using(Html.BeginForm()) 
{ 

    @Html.DropDownListFor(x=>x.SelectedLocationId, 
        new SelectList(Model.Locations ,"Id", 
        "Name"),"Select Location") 

    <input type="submit" value="Save" /> 
} 

現在寫一個HTTPPost actionmethod處理表單後（當用戶提交表單）

[HttpPost] 
public ActionResult Register(CompanyViewModel model) 
{ 
if(ModelState.IsValid) 
{ 
    // You will have selected Location id available in model.SelectedLocationId property now 
    //Save and redirect. 
} 
//Model Validation failed. so Let us reload the locations again 
//because HTTP is stateless and ASP.NET MVC is true to HTTP ! :) 
model.Locations =myRepositary.GetAllLocations(); 
return View(model); 
} 

Answer 3

下面是一些示例代碼，您可以修改和使用您的方案。我不知道你的代碼是什麼樣的，所以我創建了自己的代碼。

在你看來：

@model YourProject.ViewModels.YourViewModel 

你的位置下拉菜單：

<td><b>Location:</b></td> 
<td> 
    @Html.DropDownListFor(
      x => x.LocationId, 
      new SelectList(Model.Locations, "Id", "Name", Model.LocationId), 
      "-- Select --" 
    ) 
    @Html.ValidationMessageFor(x => x.LocationId) 
</td> 

您的視圖模型：

public class YourViewModel 
{ 
    // Partial class 

    public int LocationId { get; set; } 
    public IEnumerable<Location> Locations { get; set; } 
} 

您創建操作方法：

public ActionResult Create() 
{ 
    YourViewModel viewModel = new YourViewModel 
    { 
      // Get all the locations from the database 
      Locations = locationService.FindAll().Where(x => x.IsActive) 
    } 

    // Return the view model to the view 
    // Always use a view model for your data 
    return View(viewModel); 
} 

[HttpPost] 
public ActionResult Create(YourViewModel viewModel) 
{ 
    if (!ModelState.IsValid) 
    { 
      viewModel.Locations = locationService.FindAll().Where(x => x.IsActive); 

      return View(viewModel); 
    } 

    // If you browse the values of viewModel you will see that LocationId will have the 
    // value (unique identifier of location) already set. Now that you have this value 
    // you can do with it whatever you like. 
} 

您的位置類：

public class Location 
{ 
    public int Id { get; set; } 
    public string Name { get; set; } 
    public bool IsActive { get; set; } 
} 

這是簡單的可以來。我希望這有助於:)

UPDATE：

我的服務層是沒有任何進一步的業務邏輯，然後調用我的倉庫層從數據庫中獲取數據。我首先使用實體​​框架代碼。我也爲我的IoC容器使用Autofac。

您的服務層：

public class LocationService : ILocationService 
{ 
    private readonly ILocationRepository locationRepository; 

    public LocationService(ILocationRepository locationRepository) 
    { 
      this.locationRepository = locationRepository; 
    } 

    public IEnumerable<Location> FindAll() 
    { 
      return locationRepository.FindAll(); 
    } 
} 

而且你的資料庫：

public class LocationRepository : ILocationRepository 
{ 
    YourDbContext db = new YourDbContext(); 

    public IEnumerable<Location> FindAll() 
    { 
      return db.Locations.OrderBy(x => x.Name); 
    } 
} 

您的數據庫上下文類：

public class YourDbContext : DbContext 
{ 
    public DbSet<Location> Locations { get; set; } 
}