選擇SelectListItem模型

Question

我有一個列表傳遞給我的看法在ViewBag：

public ActionResult ContactUs() 
    { 
     List<SelectListItem> reasons = new List<SelectListItem>(); 
     reasons.Add(new SelectListItem 
     { 
      Selected = true, 
      Text = "Billing/Payment question", 
      Value = "Billing/Payment question" 
     }); 
     reasons.Add(new SelectListItem 
     { 
      Text = "Complaint", 
      Value = "Complaint" 
     }); 

     ViewBag.reasons = reasons; 
     return View(); 
    } 

[HttpPost] 
public ActionResult ContactUs(ContactUs form) 
{ 
    //some code 
    return View("ContactUs"); 
} 

型號：

[Required] 
public String Reason { get; set; } 

教職員：

@model #####.ViewModels.ContactUs 
@using (Html.BeginForm("ContactUs","Home", FormMethod.Post)) 
{ 
    @Html.DropDownListFor(Model => Model.Reason, (IEnumerable<SelectListItem>) ViewBag.reasons); 
} 

我需要創建一個下拉列表，也許DropDownList（「原因」）（應該是更好的書寫方式）形成ViewBag.reasons，並通過選擇將td值賦給我的Model，作爲屬性String Reason。只是混淆了DropDownList/DropDownListFor的使用。 謝謝！

Answer 1

型號：

public class MyModel 
{ 
    [Required] 
    public String Reason { get; set; } 
} 

控制器：

public ActionResult Index() 
{ 
    var reasons = new List<SelectListItem>(); 
    reasons.Add(new SelectListItem 
    { 
     Selected = true, 
     Text = "Billing", 
     Value = "Billing" 
    }); 
    reasons.Add(new SelectListItem 
    { 
     Text = "Complaint", 
     Value = "Complaint" 
    }); 
    ViewBag.reasons = reasons; 
    return View(new MyModel()); 
} 

查看：

@model MyModel 
... 
@Html.DropDownListFor(
    x => x.Reason, 
    (IEnumerable<SelectListItem>)ViewBag.reasons, 
    "-- select a reason --" 
) 

---

但我會建議你擺脫ViewBag和使用真正的視圖模型：

public class MyViewModel 
{ 
    [Required] 
    public string Reason { get; set; } 

    public IEnumerable<SelectListItem> Reasons { get; set; } 
} 

，然後控制器動作將填充視圖模型，並將其傳遞給視圖：

public ActionResult MyAction() 
{ 
    var reasons = new List<SelectListItem>(); 
    reasons.Add(new SelectListItem 
    { 
     Text = "Billing", 
     Value = "Billing" 
    }); 
    reasons.Add(new SelectListItem 
    { 
     Text = "Complaint", 
     Value = "Complaint" 
    }); 

    var model = new MyViewModel 
    { 
     // Notice how I am using the Reason property of the view model 
     // to automatically preselect a given element in the list 
     // instead of using the Selected property when building the list 
     Reason = "Billing", 
     Reasons = reasons 
    }; 

    return View(model); 
} 

在強類型視圖

最後：

@model MyViewModel 
... 
@Html.DropDownListFor(
    x => x.Reason, 
    Model.Reasons, 
    "-- select a reason --" 
)