如何使用数据注解的下拉列表？ [英] How to use data annotations for drop-down lists?

问题描述

在MVC3数据注释可用于加快UI开发和验证;即

In MVC3 data annotations can be used to speed up the UI development and validations; ie.

    [Required]
    [StringLength(100, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 6)]
    [DataType(DataType.Password)]
    [Display(Name = "New password")]
    public string NewPassword { get; set; }

但是，如果在移动应用中，没有字段标签，只能从数据库填充下拉列表。我怎么会这样定义这个？

However, if for a mobile app, there is no field label, only a drop-down list populated from the database. How would I define this in this way?

    [Required]
    [DataType(DataType.[SOME LIST TYPE???])]
    [Display(Name = "")]
    public string Continent { get; set; }

它是最好不要使用这种方法呢？

Is it better not to use this method for this?

推荐答案

更改您的视图模型像这样

Change your ViewModel like this

public class RegisterViewModel
{
   //Other Properties

   [Required]
   [Display(Name = "Continent")]
   public string SelectedContinent { set; get; }
   public IEnumerable<SelectListItem> Continents{ set; get; }

}

和在 GET Action方法，将您的数据库获取数据和设置您的视图模型的大洲集合属性。

and in your GET Action method, Set the Get the Data from your DB and set the Continents Collection property of your ViewModel

public ActionResult DoThatStep()
{
  var vm=new RegisterViewModel();
  //The below code is hardcoded for demo. you may replace with DB data.
  vm.Continents= new[]
  {
    new SelectListItem { Value = "1", Text = "Prodcer A" },
    new SelectListItem { Value = "2", Text = "Prodcer B" },
    new SelectListItem { Value = "3", Text = "Prodcer C" }
  }; 
  return View(vm);
}

和在查看（ DoThatStep.cshtml ）使用

@model RegisterViewModel
@using(Html.BeginForm())
{
  @Html.ValidationSummary()

  @Html.DropDownListFor(m => m.SelectedContinent, 
               new SelectList(Model.Continents, "Value", "Text"), "Select")

   <input type="submit" />
}

现在这会让你的下拉必填字段。

Now this will make your DropDown Required field.

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