DropDownList不能在ASP.Net中工作100％MVC

Question

我很困惑如何有效地使用ASP.NET MVC的Html.DropDownList助手。

背景：我有一个5页的表单，每次单击“下一步”时将数据保存到表单中。用户可以在部分之间来回导航，因此以前的部分将已经预填充了先前输入的数据。

这适用于TextBoxes。但不是DropDownLists。我曾尝试不同的方法的负载，包括：

• How to add static list of items in MVC Html.DropDownList()
• Setting selected item to DropdownList in MVC Application?

我有一个视图模型等taht我有我的名单，我的模型（生成的LINQ到SQL类）作为属性。例如：

public class ConsultantRegistrationFormViewModel 
{ 
    public IConsultantRegistration ConsultantRegistration { get; private set; } 

    public SelectList Titles { get; private set; } 
    public SelectList Countries { get; private set; } 
    public SelectList Currencies { get; private set; } 
    public int CurrentSection { get; private set; } 

    private ConsultantRegistrationFormViewModel(IConsultantRegistration consultantRegistration) 
    { 
     ConsultantRegistration = consultantRegistration; 


     CurrentSection = 1; 

     Titles = new SelectList(new string[] { "Mr", "Mrs", "Miss", "Ms", "Dr", "Sir" }); 
     Countries = new SelectList(countries.Select(q => q.Name)); 
     Currencies = new SelectList(currencies,"CurrencyCode","FriendlyForm"); 
    } 
} 

上得到我的控制器的编辑操作是这样的：

public class ConsultantRegistrationController : Controller 
{ 
     public IConsultantRegistrationRepository ConsultantRegistrationRepository { get; private set; } 
     public ICountryRepository CountryRepository { get; private set; } 
    public IEnumerable<ICountry> Countries { get; private set; } 

    public ConsultantRegistrationController() 
    { 
     ConsultantRegistrationRepository = RepositoryFactory.CreateConsultantRegistrationRepository(); 
     CountryRepository = RepositoryFactory.CreateCountryRepository(); 

     Countries = CountryRepository.GetCountries().ToArray(); 
    } 


    public ActionResult Edit(Guid id, int sectionIndex) 
    { 
     IConsultantRegistration consultantRegistration = ConsultantRegistrationRepository.GetConsultantRegistration(id); 

     SelectList bankBranchCountriesSelectList = new SelectList(Countries, "BankBranchCountry", "CountryName", consultantRegistration.BankBranchCountry); 
     ViewData["bankBranchCountrySelectList"] = bankBranchCountriesSelectList; 

     return View(new ConsultantRegistrationFormViewModel(consultantRegistration,sectionIndex, Countries,Currencies)); 
    } 
} 

我的观点做：

 <%: Html.DropDownList("ConsultantRegistration.BankBranchCountry",ViewData["bankBranchCountrySelectList"] as SelectList) %> 

这给我的错误：

DataBinding: 'IWW.ArrowPay.ConsultantRegistration.Data.Country' does not contain a property with the name 'BankBranchCountry'.

它所做的，看看架构此属性的：

public interface IConsultantRegistration 
{ 
    Guid ID { get; set; } 


    [DisplayName("Branch Country")] 
    string BankBranchCountry { get; set; } 

} 

（我的LINQ到SQL类型ConsultantRegistration实现IConsultantRegistration）

看来，它正试图绑定到错误类型有关系吗？

如果我用这个在我看来（和使用我的控制器的国家属性）：

 <%: Html.DropDownList("ConsultantRegistration.BankBranchCountry ",Model.Countries,"(select a Country)") %> 

我得到保存的值很好，但我的模型不会在之后的更新。

如果我用这个在我看来：在我的视图模型

 <%: Html.DropDownListFor(model=>model.ConsultantRegistration.BankBranchCountry ",Model.Countries,"(select a Country)") %> 

我得到的名单，并将其职位所选择的值改回，但不预先选择当前选定的项目。

所以我有一个解决方案遍布各地，但不是全部在一个地方。

希望你能帮助填补我的无知。

Answer 1

好吧，我解决了这个问题。适当的哈克，但它完成了工作。

我使用的ViewData在我看来：

   <%: Html.DropDownList("bankBranchCountrySelectList", ViewData["bankBranchCountrySelectList"] as SelectList)%> 

在我的控制下：

 public ActionResult Edit(Guid id, int sectionIndex) 
     { 
      IConsultantRegistration consultantRegistration = ConsultantRegistrationRepository.GetConsultantRegistration(id); 

      ViewData["bankBranchCountrySelectList"] = Countries.Select(q => new SelectListItem() { Text = q.Name, Value = q.Name, Selected = (q.Name.Trim().Equals(consultantRegistration.BankBranchCountry, StringComparison.InvariantCultureIgnoreCase)) }); // bankBranchCountriesSelectList; 

      return View(new ConsultantRegistrationFormViewModel(consultantRegistration,sectionIndex, Countries,Currencies)); 
     } 



     [AcceptVerbs(HttpVerbs.Post)] 
     public ActionResult Edit(Guid id, int sectionIndex, FormCollection formValues) 
     { 
      IConsultantRegistration consultantRegistration = ConsultantRegistrationRepository.GetConsultantRegistration(id); 

      UpdateModel(consultantRegistration); 
        ViewData["bankBranchCountrySelectList"] = Countries.Select(q => new SelectListItem() { Text = q.Name, Value = q.Name, Selected = (q.Name.Trim().Equals(consultantRegistration.BankBranchCountry, StringComparison.InvariantCultureIgnoreCase)) }); 

      IEnumerable<RuleViolation> ruleViolations = consultantRegistration.GetRuleViolations(sectionIndex); 
      if (ruleViolations.Count() == 0) 
      { 

// ... 
      } 
      else 
      { 
       ModelState.AddRuleViolations(ruleViolations); 
       return View(new ConsultantRegistrationFormViewModel(consultantRegistration, sectionIndex, Countries, Currencies)); 
      } 


    } 

不理想中断清洁编码。不知道它为什么起作用，但这似乎是MVC关于“约定优于配置”的全部内容。

Answer 2

文章在考虑多选择列表写的，但其原理同样适用于单一选择下拉列表：

http://www.stevefenton.co.uk/Content/Blog/Date/201002/Blog/How-To-Handle-Multiple-Select-Lists-In-ASP-NET-MVC/