GridView1_PageIndexChanging 在索引更改时不更改答案

【问题标题】：GridView1_PageIndexChanging not changing when index changingGridView1_PageIndexChanging 在索引更改时不更改
【发布时间】：2014-01-02 11:33:26
【问题描述】：

我试图一次显示 50 个。它应该在“页面索引”更改时激活。原始的 Gridview 可以工作并且有 1000 多个条目。 GridView1_PageIndexChanging 或 GridView1.PageIndex = e.NewPageIndex 不起作用。这是我的代码：

    <asp:GridView ID="GridView1" runat="server" AllowPaging="True" PageSize="50" OnPageIndexChanging="GridView1_PageIndexChanging">
    </asp:GridView>

  Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs) Handles GridView1.PageIndexChanging
    GridView1.PageIndex = e.NewPageIndex
    Dim connStr, cmdStr As String
    Dim myDataSet As New DataSet
    Dim dt As New DataTable()
    connStr = "connection string works"
    cmdStr = "SELECT * FROM table1;"
    Try
        Using conn As New SqlConnection(connStr)
            Using cmd As New SqlCommand(cmdStr, conn)
                conn.Open()
                cmd.ExecuteNonQuery()
                Using myDataAdapter As New SqlDataAdapter(cmd)
                    myDataAdapter.Fill(myDataSet)
                    dt = myDataSet.Tables(0)
                    Dim filteredSet = dt.AsEnumerable().Skip((GridView1.PageIndex - 1) * 50)
                    GridView1.DataSource = filteredSet
                    GridView1.DataBind()
                End Using
                conn.Close()
                cmd.Dispose()
                conn.Dispose()
            End Using
        End Using
    Catch ex As Exception

    End Try
 End Sub

【问题讨论】：

我认为你应该使用CustomersGridView_PageIndexChanged事件而不是CustomersGridView_PageIndexChanging
从 Gridview1_PageIndexChanging 更改为 Gridview1_PageIndexChanged 只是导致应用程序错误。

标签： asp.net vb.net gridview

【解决方案1】：

如果您允许，GridView 将为您处理分页。您不需要自己过滤查询。我有几个建议：

集中您的数据绑定代码
将所有数据绑定代码放在一个集中的函数中。这将使您的 PageIndexChanging 事件看起来更清晰，并降低拼写错误的风险（如果您必须在其他地方复制该代码）。应该是这样的：

Private Sub BindGrid()
    Dim connStr, cmdStr As String
    Dim myDataSet As New DataSet
    Dim dt As New DataTable()
    connStr = "connection string works"
    cmdStr = "SELECT * FROM table1;"
    Try
        Using conn As New SqlConnection(connStr)
            Using cmd As New SqlCommand(cmdStr, conn)
                conn.Open()
                cmd.ExecuteNonQuery()
                Using myDataAdapter As New SqlDataAdapter(cmd)
                    myDataAdapter.Fill(myDataSet)
                    dt = myDataSet.Tables(0)
                    GridView1.DataSource = dt
                    GridView1.DataBind()
                End Using
                conn.Close()
            End Using
        End Using
    Catch ex As Exception

    End Try
End Sub

注意：我把你的电话打给Dispose，因为它们是多余的（Using 块就是这样做的）

更新您的 PageIndexChanging 代码以调用该子
现在您可以为分页提供清理功能：

Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs) Handles GridView1.PageIndexChanging
    GridView1.PageIndex = e.NewPageIndex
    BindGrid() 
End Sub

优化：以某种方式缓存您的数据库调用
每次对 GridView 进行分页时，您不需要从数据库中检索 1,000 多行。第一次加载 Grid 时将 DataTable 放入 Session 变量中（我想是在 Page_Load 中）：

Session("myGridViewData") = dt

然后在您再次需要时（例如在寻呼期间）将其从那里取出：

Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs) Handles GridView1.PageIndexChanging
    GridView1.PageIndex = e.NewPageIndex
    Gridview1.DataSource = CType(Session("myGridViewData"), DataTable)
    GridView1.DataBind()        
End Sub

【讨论】：