ASP .NET MVC 3 DropDownListFor问题

Question

在模型中，我有：

public Guid? Country 
{ get; set; } 

在视图中，我有：

@Html.DropDownListFor(m => m.Country, (SelectList)ViewBag.Countries) 

提交时，错误occures，因为它要保存字符串Guid。如何保存该值而不是下拉列表的文本？

Answer 1

好的。用一点不同的方法来解决问题。

型号：

public UserRegistrationModel() 
{ 
    this.InitializeCountries(); 
} 

private void InitializeCountries() 
{ 
    FarmerEntities fe = new FarmerEntities(); 
    var query = from c in new FarmerEntities().Countries select new { ID = c.ID_Country, Name = c.ISO_Code }; 
    var countries = query.ToSelectList(c => c.ID.ToString(), c => c.Name); 

    this.Countries = countries; 
} 

public Guid? { get; set; } 

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

控制器：

UserRegistrationModel model = new UserRegistrationModel(); 

return View(model); 

查看：

@Html.DropDownListFor(m => m.Country, Model.Countries, "") 

此外，您还需要实现这种扩展

public static class EnumerableExtensions 
{ 
    public static IEnumerable<SelectListItem> ToSelectList<TItem, TValue>(this IEnumerable<TItem> items, Func<TItem, TValue> valueSelector, Func<TItem, string> nameSelector) 
    { 
     return items.ToSelectList(valueSelector, nameSelector, x => false); 
    } 

    public static IEnumerable<SelectListItem> ToSelectList<TItem, TValue>(this IEnumerable<TItem> items, Func<TItem, TValue> valueSelector, Func<TItem, string> nameSelector, IEnumerable<TValue> selectedItems) 
    { 
     return items.ToSelectList(valueSelector, nameSelector, x => selectedItems != null && selectedItems.Contains(valueSelector(x))); 
    } 

    public static IEnumerable<SelectListItem> ToSelectList<TItem, TValue>(this IEnumerable<TItem> items, Func<TItem, TValue> valueSelector, Func<TItem, string> nameSelector, Func<TItem, bool> selectedValueSelector) 
    { 
     foreach (var item in items) 
     { 
      var value = valueSelector(item); 

      yield return new SelectListItem 
      { 
       Text = nameSelector(item), 
       Value = value.ToString(), 
       Selected = selectedValueSelector(item) 
      }; 
     } 
    } 
}