我有以下代码（ASP.NET MVC / C＃）...为了简洁起见，简化了一些代码。
public class UserViewModel
{
public int UserId { get; set; }
public string Name { get; set; }
public AddressViewModel Address { get; set; }
public IEnumerable<SelectListItem> CitySelectList { get; set; }
}
public class AddressViewModel
{
public int AddressId { get; set; }
public string StreetAddress { get; set; }
public int CityId { get; set; }
}
在剃须刀视图中，我有以下内容：
@Html.DropDownListFor(x => x.Address.CityId, Model.CitySelectList)
在加载时的下拉列表中选择正确的城市（即......原始值）以便工作正常，但是当我提交表单时，CityId属性不会使用新选择的值进行更新....它仍然包含原始城市的id。
我向UserViewModel添加了一个名为＆＃34; SelectedCityId＆＃34;的新属性。并将其绑定到像这样的下拉列表，以测试复杂的嵌套对象是问题：
@Html.DropDownListFor(x => x.SelectedCityId, Model.CitySelectList)
当我使用此方法提交表单时，SelectedCityId确实包含正确的id，因此当对象是一个简单的对象时，我可以看到模型绑定正常工作，但是当它是一个嵌套的子对象时，它不能正常工作。
仅仅为了排除故障，我检查了邮政编码字段，因为它也绑定到Address类的子属性，但是在使用类似的TextBoxFor帮助程序时它确实正确绑定：
@Html.TextBoxFor(x => x.Address.PostalCode)
所以，我的问题是，当表达式将控件绑定到嵌套的子属性时，为什么模型绑定似乎不适用于DropDownListFor帮助器？我确定它缺少一些微不足道的东西，但是我没看到它是什么，并且在这里没有找到类似的答案。
编辑： 这是cshtml文件中的整个html表单
@using (Html.BeginForm("MyProfile", "Account", FormMethod.Post, new { id = "myProfileForm" }))
{
@Html.HiddenFor(x => x.UserId)
@Html.HiddenFor(x => x.AddressId)
@Html.HiddenFor(x => x.Address.CityId)
<article class="mysettings">
<h1>Personal details</h1>
<table>
<tr>
<th>E-mail:</th>
<td>@Model.Username
<!--edit fields-->
<div class="edit_field" id="field3">
<label for="new_email">New Email:</label>
@Html.TextBoxFor(x => x.Username, new { id = "new_email" })
<input type="submit" value="save" class="gradient-button" id="submit3"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td></td>
</tr>
<tr>
<th>First name:</th>
<td>@Model.FirstName
<!--edit fields-->
<div class="edit_field" id="field1">
<label for="new_name">New First Name:</label>
@Html.TextBoxFor(x => x.FirstName, new { id = "new_name" })
<input type="submit" value="save" class="gradient-button" id="submit1"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field1" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Last name:</th>
<td>@Model.LastName
<!--edit fields-->
<div class="edit_field" id="field2">
<label for="new_last_name">New Last Name:</label>
@Html.TextBoxFor(x => x.LastName, new { id = "new_last_name" })
<input type="submit" value="save" class="gradient-button" id="submit2"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field2" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Display name:</th>
<td>@Model.DisplayName
<!--edit fields-->
<div class="edit_field" id="field_display">
<label for="new_display_name">New Display Name:</label>
@Html.TextBoxFor(x => x.DisplayName, new { id = "new_display_name" })
<input type="submit" value="save" class="gradient-button" id="submit_display"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field_display" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Password:</th>
<td><input type="password" value="@Model.Membership.Password" disabled="disabled" style="border: none; background-color: white; padding: 0;" />
<!--edit fields-->
<div class="edit_field" id="field4">
<label for="new_password">New Password:</label>
@Html.PasswordFor(x => x.Membership.Password, new { id = "new_password" })
<input type="submit" value="save" class="gradient-button" id="submit4"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td></td>
</tr>
<tr>
<th>Cell phone:</th>
<td>@Model.CellPhone
<!--edit fields-->
<div class="edit_field" id="field_cell">
<label for="new_cell">New Cell Phone:</label>
@Html.TextBoxFor(x => x.CellPhone, new { id = "new_cell" })
<input type="submit" value="save" class="gradient-button" id="submit_cell"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field_cell" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Home phone:</th>
<td>@Model.HomePhone
<!--edit fields-->
<div class="edit_field" id="field_home">
<label for="new_home">New Home Phone:</label>
@Html.TextBoxFor(x => x.HomePhone, new { id = "new_home" })
<input type="submit" value="save" class="gradient-button" id="submit_home"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field_home" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Street Address:</th>
<td>@(Model.Address != null ? Model.Address.Address1 : "No address given")
<!--edit fields-->
<div class="edit_field" id="field5">
<label for="new_address">New Address:</label>
@Html.TextBoxFor(x => x.Address.Address1, new { id = "new_address" })
<input type="submit" value="save" class="gradient-button" id="submit5"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field5" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Town / City:</th>
<td>@(Model.Address != null ? Model.Address.City.Name : "No address given")
<!--edit fields-->
<div class="edit_field" id="field6">
<label for="new_city">New City:</label>
@Html.DropDownListFor(x => x.Address.CityId, Model.CitySelectList, new { @class = "f-item" })
<input type="submit" value="save" class="gradient-button" id="submit6"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field6" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Postal Code:</th>
<td>@(Model.Address != null ? Model.Address.PostalCode : "No address given")
<!--edit fields-->
<div class="edit_field" id="field7">
<label for="new_zip">New Postal Code:</label>
@Html.TextBoxFor(x => x.Address.PostalCode, new { id = "new_zip" })
<input type="submit" value="save" class="gradient-button" id="submit7"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field7" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>First Admin Division (State):</th>
<td>@(Model.Address != null ? Model.Address.City.FirstAdminDivision.Name : "No address given")
<!--edit fields-->
<div class="edit_field" id="field8">
<label for="new_state">New First Admin Division (State):</label>
<input type="text" id="new_state"/>
<input type="submit" value="save" class="gradient-button" id="submit8"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field8" class="gradient-button edit">Edit</a></td>
</tr>
<tr>
<th>Country:</th>
<td>@(Model.Address != null ? Model.Address.City.FirstAdminDivision.Country.Name : "No address given")
<!--edit fields-->
<div class="edit_field" id="field9">
<label for="new_country">New Country:</label>
<input type="text" id="new_country"/>
<input type="submit" value="save" class="gradient-button" id="submit9"/>
<a href="#">Cancel</a>
</div>
<!--//edit fields-->
</td>
<td><a href="#field8" class="gradient-button edit">Edit</a></td>
</tr>
</table>
</article>
}
两个控制器动作：
public ActionResult MyProfile()
{
IAccountService accountSvc = GetService<IAccountService>();
UserProfileServiceRequest request = new UserProfileServiceRequest();
int userId = int.Parse(SessionMgr.GetInstance().GetSessionValue(SessionTypes.UserId).ToString());
if (userId == 0)
{
return RedirectToAction("Login", "Account");
}
else
{
request.UserId = userId;
UserProfileServiceResponse response = accountSvc.GetUserProfile(request);
UserProfileViewModel model = AutoMapper.Mapper.Map<UserProfileViewModel>(response.UserProfile);
ICommonService commonSvc = GetService<ICommonService>();
GetCitiesServiceRequest citiesRequest = new GetCitiesServiceRequest { FirstAdminDivisionId = model.Address.City.FirstAdminDivision.FirstAdminDivisionId };
KeyValuePairServiceResponse citiesResponse = commonSvc.GetCitiesForSelect(citiesRequest);
model.CitySelectList = citiesResponse.KeyValuePairs.ToSelectList();
List<RoleViewModel> roles = (List<RoleViewModel>)SessionMgr.GetInstance().GetSessionValue(SessionTypes.Roles);
RoleViewModel consumerRole = roles.FirstOrDefault(x => x.Meaning.Equals(DataEnumerations.GetRoleMeaning(DataEnumerations.Role.Consumer)));
if (consumerRole != null)
{
GetConsumerTripsServiceRequest consumerTripsRequest = new GetConsumerTripsServiceRequest() { UserId = userId };
GetConsumerTripsServiceResponse consumerTripsResponse = commonSvc.GetConsumerTrips(consumerTripsRequest);
model.ConsumerTrips = AutoMapper.Mapper.Map<List<TripViewModel>>(consumerTripsResponse.Trips);
GetUserReviewsServiceRequest userReviewsRequest = new GetUserReviewsServiceRequest() { UserId = userId };
GetUserReviewsServiceResponse userReviewsResponse = commonSvc.GetUserReviews(userReviewsRequest);
model.UserReviews = AutoMapper.Mapper.Map<List<UserReviewViewModel>>(userReviewsResponse.UserReviews);
}
return View(model);
}
}
[HttpPost]
public ActionResult MyProfile(UserProfileViewModel model)
{
UpdateUserProfileServiceRequest request = AutoMapper.Mapper.Map<UpdateUserProfileServiceRequest>(model);
IAccountService accountSvc = GetService<IAccountService>();
accountSvc.UpdateUserProfile(request);
return RedirectToAction("MyProfile", "Account");
}
整个AddressViewModel类：
public class AddressViewModel
{
public Int32 AddressId { get; set; }
public String Address1 { get; set; }
public String Address2 { get; set; }
public Int32 CityId { get; set; }
public String PostalCode { get; set; }
public CityViewModel City { get; set; }
}
整个UserProfileViewModel：
public class UserProfileViewModel : BaseViewModel
{
public int UserId { get; set; }
public string Username { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string DisplayName { get; set; }
public string CellPhone { get; set; }
public string HomePhone { get; set; }
public int AddressId { get; set; }
public AddressViewModel Address { get; set; }
public MembershipViewModel Membership { get; set; }
public List<TripViewModel> ConsumerTrips { get; set; }
public List<UserReviewViewModel> UserReviews { get; set; }
public IEnumerable<SelectListItem> CitySelectList { get; set; }
public int SelectedCityId { get; set; }
}
答案 0 :(得分：2)
除了下拉列表
之外，您的表单还包含该属性的隐藏输入@Html.HiddenFor(x => x.Address.CityId)
....
@Html.DropDownListFor(x => x.Address.CityId, Model.CitySelectList, ..)
实际上，您传回的是同一属性的2个值。 DefaultModelBinder读取第一个（来自隐藏输入，即原始值）并设置Address.CityId的值。
删除隐藏的输入，您的模型将与所选值正确绑定。