我已经解决了一个问题,我正在使用asp.net mvc4应用程序并简化它,所以我可以在这里发布它.我的基本问题是我正在尝试将项目列表发送到我的视图并编辑任何项目的复选框,然后将列表项目发送回控制器并最终保存到数据库.当我将列表发送回控制器时,代码的编写方式就像一个空值一样,就像从未实例化过一样.
代码如下：
Public Class Person
Property ID As Integer
Property Name As String
Property Active As Boolean
End Class
在控制器中,我调用了一个名为BuildPeople的类,它实际上只是一种构建要传递的列表的方法：
Public Class BuildPeople
Public Function GetPersonList() As List(Of Person)
Dim personList As New List(Of Person)
personList.Add(GetPerson(1,"Chris",True))
personList.Add(GetPerson(2,"Ken",True))
personList.Add(GetPerson(3,"Jen",True))
Return personList
End Function
Private Function GetPerson(id As Integer,name As String,active As Boolean) As Person
Dim p As New Person
p.ID = id
p.Name = name
p.Active = active
Return p
End Function
End Class
控制器只具有编辑功能：
Imports System.Web.Mvc
Public Class PeopleController
Inherits Controller
' GET: /People
Function Index() As ActionResult
Return View()
End Function
' GET: /People/Edit/5
Function Edit() As ActionResult
Dim bp As New BuildPeople
Dim model As New List(Of Person)
model = bp.GetPersonList
ViewData.Model = model
Return View()
End Function
' POST: /People/Edit/5
<HttpPost()>
Function Edit(ByVal listPeople As List(Of Person)) As ActionResult
Try
' TODO: Add update logic here
If listPeople Is Nothing Then
'Don't want to end up here
Return View()
Else
'Want to end up here
Dim i As Integer = listPeople.Count
Return View()
End If
Catch
Return View()
End Try
End Function
End Class
然后视图如下：
@ModelType List(Of Person)
@Code
ViewData("Title") = "Edit"
Layout = "~/Views/Shared/_Layout.vbhtml"
End Code
<h2>Edit</h2>
@Using (Html.BeginForm())
@Html.AntiForgeryToken()
@<div class="form-horizontal">
<h4>Person</h4>
<hr />
@For Each item In Model
Dim currentitem = item
@Html.HiddenFor(Function(model) currentitem.ID)
@Html.EditorFor(Function(model) currentitem.Name)
@Html.EditorFor(Function(model) currentitem.Active)
Next
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Save" class="btn btn-default" />
</div>
</div>
</div>
End Using
<div>
@Html.ActionLink("Back to List","Index")
</div>
因此,您必须了解HTML表单的工作方式以及MVC模型绑定器的工作原理.
如果选中复选框,则仅在后期数据中发回一个值.
接下来,只要字段命名遵循正确的命名约定,MVC中的模型绑定器将重新构建集合/列表对象.
因此,对于模型中的每个项目,您的循环需要生成具有正确名称的项目.
让我们稍微改变你的模型.
Public Class PeopleModel Public Property People As List(Of Person) Public Property SelectedPeople As List(Of Int64) ' Assuming Person.ID is Int64 End Class
然后你改变你的视图循环,如下所示：
Dim itemIndex As Int32 = 0 For Each person As Person In Model.People @<input type='checkBox' name='SelectedPeople[@itemIndex]' id='person_@person.ID' value='@person.ID' /> @<input type='hidden' name='SelectedPeople[@itemIndex]' value='-1' /> itemIndex += 1 Next
我们将隐藏元素放在那里,因为它将为未检查的项提供字段值.否则,第一个未检查的项目将破坏索引,模型绑定器将停止.
现在在你的控制器的post处理程序中：
<HttpPost>
Public Function ActionName(model As PeopleModel) As ActionResult
For Each id As Int64 In model.SelectedPeople
If 0 < id Then
' This is the id of a selected person - do something with it.
End If
Next
End Function