通过的SelectList＆QUOT;＆的SelectedValue QUOT;到控制器的操作方法 [英] Pass SelectList "SelectedValue" to Controller Action Method
问题描述
我有这显示一个用户名（文本），电子邮件（文本）和科（的SelectList）登记表。姓名和电子邮件是pre-填充（我使用的是Windows身份验证，联网的应用程序），我想从下拉列表中的SelectedValue发送到我的控制器作为一个Int32，我不希望将整个的SelectList背部。这份名单是小了，但将增长到相当的规模。
I have a registration form which displays a users Name (textbox), Email (textbox) and Division (SelectList). The Name and Email are pre-populated (I'm using Windows Authentication, Intranet app), and I want to send the SelectedValue from the DropDown to my controller as an Int32, I don't want to send the entire SelectList back. This list is small now, but will grow to considerable size.
我一个名为 RegistrationViewModel 类，它包含了这些领域的公共属性。然而，当我使用的SelectList 为DivisionList，我收到此错误：此对象定义无参数的构造函数。
I a class called RegistrationViewModel, it contains public properties for these fields. However, when I use SelectList for the DivisionList, I receive this error: No parameterless constructor defined for this object..
如果我改变类型，它的工作原理没有问题，但司为空或0。有没有办法从下拉列表中的SelectedValue传递给控制器的操作方法为的Int32？
If i change the Type, it works no problem, but Division is null or 0. Is there a way to pass the SelectedValue from a DropDown to a Controller Action method as a Int32?
我真的不知道我在做什么，我一直在使用MVC约48小时，观看PDF，微软技术教育大会，并TechDays视频。
I'm not really sure what I'm doing, I've been using MVC for about 48 hours, watched the PDF, TechEd, and TechDays videos.
我的道歉，这里是我的控制器code：
My apologies, here is my controller code:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Register(RegistrationViewModel rvm)
{
IApplicationContext context = ContextRegistry.GetContext();
IValidationErrors errors = new ValidationErrors();
IValidator validator = (IValidator)context.GetObject("RegistrationValidator");
bool valid = validator.Validate(rvm, errors);
if (valid)
repo.SaveRegistration();
else
ViewData["DivisionList"] = repo.GetDivisions();
return View(rvm);
}
RegistrationViewModel 类
public class RegistrationViewModel
{
public string Name { get; set; }
public string Email { get; set; }
//public SelectList DivisionList { get; private set; }
public int Division { get; set; }
}
下面是该视图
<%@ Page Language="C#"
MasterPageFile="~/Views/Shared/Site.Master"
Inherits="System.Web.Mvc.ViewPage<RegistrationViewModel>" %>
<%@ Import Namespace="Project1.Entities"%>
<%@ Import Namespace="Project1.Models"%>
<asp:Content ID="registerTitle" ContentPlaceHolderID="TitleContent" runat="server">
Register
</asp:Content>
<asp:Content ID="registerContent" ContentPlaceHolderID="MainContent" runat="server">
...
<% using (Html.BeginForm())
{ %>
<div>
<fieldset>
<legend>Account Information</legend>
<p>
<label for="name">Name:</label>
<%= Html.TextBox("Name", User.Identity.Name.GetDisplayName()) %>
<%= Html.ValidationMessage("username") %>
</p>
<p>
<label for="email">Email:</label>
<%= Html.TextBox("email", User.Identity.Name.GetEmailFromLogin()) %>
<%= Html.ValidationMessage("email") %>
</p>
<p>
<label for="division">Division:</label>
<%= Html.DropDownList("DivisionList", ViewData["DivisionList"] as SelectList)%>
<%= Html.ValidationMessage("confirmPassword") %>
</p>
<p>
<input type="submit" value="Register" />
</p>
</fieldset>
</div>
<% } %>
</asp:Content>
修改2：
Eilon：这是我改变了它太：
Edit 2:
Eilon: Here is what I changed it too:
控制器：
public ActionResult Register()
{
ViewData["DivisionList"] = repo.GetDivisions();
return View();
}
查看：
<%= Html.DropDownList("DivisionValue", ViewData["DivisionList"] as SelectList)%>
我收到此异常：
有型的关键DivisionValue'的IEnumerable'。没有ViewData的项目
I recieve this exception: There is no ViewData item with the key 'DivisionValue' of type 'IEnumerable'.
当我查看更新，以这样的：
When I updated the View to this:
<%= Html.DropDownList("DivisionList", ViewData["DivisionList"] as SelectList)%>
它的工作好了！似乎只有工作，如果所有的科的项目同名。如果我改名字查看崩溃或视图模型项财产被作为0。
It works just great! It only seems to work if all the "Division" items named identically. If I change the name the View crashes or the ViewModel "Division" property is sent as 0.
这是为什么？
推荐答案
在 RegistrationViewModel 的类型应该包含一个简单类型的属性，如：
The RegistrationViewModel type should contain a simple-typed property such as:
public string DivisionValue { get; set; }
或改变类型为int，日期时间，或任何适当的类型。
Or change the type to int, DateTime, or whatever the appropriate type is.
在HTML和HTTP是被调回的下拉列表中的唯一的事情就是字段的名称，选择的值。
In HTML and HTTP the only thing that gets posted back for a drop down list is the name of the field and the selected value.
要得到的一切投其所好，你也需要改变的观点来呈现不同的输入名称下拉列表：
To get everything to match up you also need to change the view to render a different input name for the drop down list:
<%= Html.DropDownList("DivisionValue", ViewData["DivisionList"] as SelectList)%>
请注意，我使用DivisionValue是的值的名单，而 DivisionList 的为所有可用的项目列表。
Notice that I'm using "DivisionValue" is the value of the list, and DivisionList as the list of all available items.
这篇关于通过的SelectList＆QUOT;＆的SelectedValue QUOT;到控制器的操作方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
