Question

尝试在对象列表和数据列表控件之间使用数据绑定。我想做的是

创建对象列表
将它们绑定到控件
更改用户界面中的数据
将ui中的更改绑定到对象列表
- 拥有带有ui的新值的对象列表

<body>
    <form id="form1" runat="server">
    <div>
        <asp:DataList ID="DataList1" runat="server" DataKeyField="ClassID" ViewStateMode="Enabled">
            <ItemTemplate>
                <asp:TextBox ID="txtValue1" runat="server" Text='<%# Bind("Value1") %>'></asp:TextBox>
                <asp:TextBox ID="txtValue2" runat="server" Text='<%# Bind("Value2") %>'></asp:TextBox>
                <asp:TextBox ID="txtvalue3" runat="server" Text='<%# Bind("Value3") %>'></asp:TextBox>
            </ItemTemplate>
        </asp:DataList>
        <asp:Button ID="btnDoPostBack" runat="server" Text="Do Post Back" />
    </div>
    </form>
</body>

Option Explicit On
Option Strict On

Imports System.Diagnostics

Partial Class _Default
    Inherits System.Web.UI.Page

Dim Class1List As List(Of Class1)

Protected Sub Page_PreLoad(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreLoad
    Dim txtValue1 As TextBox
    Dim txtValue2 As TextBox
    Dim txtValue3 As TextBox
    Dim ItemIndex As Integer = 0

    If Page.IsPostBack Then
        Class1List = CType(Session("Class1List"), List(Of Global.Class1))
        'Class1List = CType(DataList1.DataSource, List(Of Global.Class1))
        For Each myDataListItem As DataListItem In DataList1.Items
            txtValue1 = CType(myDataListItem.FindControl("txtValue1"), TextBox)
            Long.TryParse(txtValue1.Text, Class1List(ItemIndex).Value1)

            txtValue2 = CType(myDataListItem.FindControl("txtValue2"), TextBox)
            Integer.TryParse(txtValue2.Text, Class1List(ItemIndex).Value2)

            txtValue3 = CType(myDataListItem.FindControl("txtValue3"), TextBox)
            Class1List(ItemIndex).Value3 = txtValue3.Text

            ItemIndex += 1
        Next
    End If
End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Dim myClass1 As Class1

    If Not Page.IsPostBack Then
        Class1List = New List(Of Class1)
        myClass1 = New Class1
        Class1List.Add(myClass1)
        BindData()
    Else
        'Class1List = CType(DataList1.DataSource, List(Of Global.Class1))
        Debug.WriteLine("Page_Load, Value1 = " & Class1List(0).Value1.ToString())
        Debug.WriteLine("Page_Load, Value2 = " & Class1List(0).Value2.ToString())
        Debug.WriteLine("Page_Load, Value3 = " & Class1List(0).Value3)
    End If
End Sub

Protected Sub Page_Unload(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Unload
    Session("Class1List") = Class1List
End Sub

Sub BindData()
    DataList1.DataSource = Class1List
    DataList1.DataBind()
End Sub

Protected Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataListItemEventArgs) Handles DataList1.ItemDataBound
    Dim myClass1 As Class1

    If e.Item.ItemType = ListItemType.Item OrElse e.Item.ItemType = ListItemType.AlternatingItem Then
        myClass1 = CType(e.Item.DataItem, Class1)
        Debug.WriteLine("DataList1_ItemDataBound, Value1 = " & myClass1.Value1.ToString())
        Debug.WriteLine("DataList1_ItemDataBound, Value2 = " & myClass1.Value2.ToString())
        Debug.WriteLine("DataList1_ItemDataBound, Value3 = " & myClass1.Value3)

    End If
End Sub

Protected Sub btnDoPostBack_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnDoPostBack.Click
    Dim myRandom As New Random

    Class1List(0).Value1 = myRandom.Next(100)
    Class1List(0).Value2 = myRandom.Next(100)
    Class1List(0).Value3 = myRandom.Next(100).ToString()
    Debug.WriteLine("btnDoPostBack_Click, Value1 = " & Class1List(0).Value1.ToString())
    Debug.WriteLine("btnDoPostBack_Click, Value2 = " & Class1List(0).Value2.ToString())
    Debug.WriteLine("btnDoPostBack_Click, Value3 = " & Class1List(0).Value3)
    BindData()
End Sub
End Class

Class Class1很简单：

Option Explicit On
Option Strict On

Imports Microsoft.VisualBasic

Public Class Class1
Private _ClassID As Long
Private _Value1 As Long
Private _Value2 As Integer
Private _value3 As String = String.Empty

Public Property ClassID As Long
    Get
        Return _ClassID
    End Get
    Set(ByVal value As Long)
        _ClassID = value
    End Set
End Property

Public Property Value1 As Long
    Get
        Return _Value1
    End Get
    Set(ByVal value As Long)
        _Value1 = value
    End Set
End Property

Public Property Value2 As Integer
    Get
        Return _Value2
    End Get
    Set(ByVal value As Integer)
        _Value2 = value
    End Set
End Property

Public Property Value3 As String
    Get
        Return _value3
    End Get
    Set(ByVal value As String)
        _value3 = value
    End Set
End Property
End Class

更新：我得到了上面的代码来做我想做的事情 - 我在想有更好的方法吗？

Answer 1

您没有显示数据绑定“加载”阶段（将数据从列表绑定到控件的代码） - 所以我假设你的部分不满意的是“保存”阶段（Page_PreLoad中的代码将修改后的值从控件绑定到到列表），即＃4 in你的清单：

将ui中的更改绑定到对象列表

听起来你想要“双向数据绑定”：你希望.NET能够像模拟中读取一样轻松地更新你的模型。这是common complaint。一个解决方案是subclass WebControl，但那是一团糟。

您已使用<%# Bind("...") %>语法，因此您有正确的想法。该方法应该与<asp:SqlDataSource>，开箱即用，但您想要更新自定义类，因此您需要使用<asp:ObjectDataSource>。使用this article中的方法，但使用ObjectDataSource而不是SqlDataSource。

但首先，您必须通过使用[System.ComponentModel.DataObject]标记并指定适当的更新方法，使您的模型（即Class1）与ObjectDataSource兼容：

[System.ComponentModel.DataObjectMethodAttribute( System.ComponentModel.DataObjectMethodType.Update, true)] public bool UpdateProduct(string productName, ...) { ... }

这将允许您在webform上使用ObjectDataSource，最后获得漂亮的双向数据绑定。阅读链接以获取完整的详细信息。

Visual Studio提供了各种笨重的自动化方式，例如TableAdapters和臭名昭着的Strongly-Typed DataSet (STD)，但这些方法无法帮助像您这样拥有自己的对象模型的人。无论如何我不推荐STD。

我在想有更好的方法吗？

我不认为你目前的方法很糟糕。如果您担心网络表格中存在大量逻辑，那么使用MVC方法可以获得更多，而不是担心绑定糖......

ASP.NET中的双向数据绑定

1 个答案: