触发DataList ItemCommand时从DataSource中删除项目

Question

我有点卡在这里。我有一个数据源，其数据源为Lit（of SomeObject）。

Private MyObjectList As List (of SomeObject)

我在用户点击按钮的同时加载数据，将产品添加到购物篮并绑定数据列表。

Form_load....
dl.Datasource = MyObjectList
dl.databind()
End Sub

要在datalist中显示数据，我有一个标签，显示他们添加的内容，使用e eventArg将其转换为我的对象，例如：

Protected Sub dl_ItemDataBound(sender As Object, e As System.Web.UI.WebControls.DataListItemEventArgs) Handles dl.ItemDataBound
    Dim myObject = DirectCast(e.Item.DataItem, SomeObject)
....
Label.Text = myObject.Description

End Sub

内联代码是：

    <asp:DataList ID="dl" runat="server">
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
                    <asp:Button ID="DeletePRoduct" runat="server" Text="Delete" CommandName="Del" CommandArgument='<%# Container.ItemIndex %>'/>
        </ItemTemplate>
    </asp:DataList>

所以现在我希望用户能够删除产品

Protected Sub dl_ItemCommand(source As Object, e As System.Web.UI.WebControls.DataListCommandEventArgs) Handles dl.ItemCommand
    Dim myObject = DirectCast(e.Item.DataItem, SomeObject)

    If e.CommandName = "Del" Then
        MyObjectList.Remove(myObject)
    ....
    End If
End Sub

如果我尝试在ItemCommand下传入myObject，我意识到我投入的e.item.DataItem是Nothing，因此它不会删除任何产品。然后我想通过行索引删除该产品，并在我意识到我无法执行此操作时向该按钮添加了一个CommandArgument，因为List需要一种SomeObject类型。

有人可以建议如何以这种方式删除对象吗？

由于

Answer 1

从数据源DataList中删除对象后，您必须再次绑定MyObjectList以获取页面上的更新记录。

If e.CommandName = "Del" Then

    MyObjectList.Remove(myObject)
    dl.Datasource = MyObjectList
    dl.databind()
....
End If

Answer 2

您可以使用dl.DataKeys[e.Item.ItemIndex]找到删除项目的ID。请务必设置DataKeyField DataList控件的<asp:DataList ID="dl" runat="server" DataKeyField="ID"...> .... </asp:DataList> Public Class SomeObject Public Property ID() As Integer Get Return m_ID End Get Set m_ID = Value End Set End Property Private m_ID As Integer Public Property Name() As String Get Return m_Name End Get Set m_Name = Value End Set End Property Private m_Name As String End Class Private _someObjects As List(Of SomeObject) Public Property SomeObjects() As List(Of SomeObject) Get If _someObjects Is Nothing Then _someObjects = New List(Of SomeObject)() With { _ New SomeObject() With { _ .ID = 1, _ .Name = "One" _ }, _ New SomeObject() With { _ .ID = 2, _ .Name = "Two" _ }, _ New SomeObject() With { _ .ID = 2, _ .Name = "Three" _ } _ } End If Return _someObjects End Get Set SomeObjects = value End Set End Property Protected Sub Page_Load(sender As Object, e As System.EventArgs) If Not IsPostBack Then dl.DataSource = SomeObjects dl.DataBind() End If End Sub Protected Sub dl_ItemCommand(source As Object, e As DataListCommandEventArgs) If e.CommandName = "Del" Then Dim id = Convert.ToInt32(dl.DataKeys(e.Item.ItemIndex)) Dim someObject = SomeObjects.First(Function(x) x.ID = id) SomeObjects.Remove(someObject) dl.DataSource = SomeObjects dl.DataBind() End If End Sub 。

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注意：删除后需要注意数据的持久性。例如，在ViewState，Session或Database中存储数据。