Question

我正在尝试在代码中对gridview进行排序。它正在工作，现在我得到了一个

对象引用未设置为对象的实例

错误。它发生在我将gridview的数据源分配给数据表的行上。这是代码部分（注意，gridivew工作和页面很好）

Protected Sub gvBasicList_Sorting(sender As Object, e As GridViewSortEventArgs)
    Dim gv As GridView = DirectCast(sender, GridView)
    Dim dv As DataView = TryCast(gv.DataSource, DataView) <ERROR HERE
    Dim dataTable As DataTable = dv.Table
    Dim sortdir As [String] = ""
    If e.SortExpression <> "" And e.SortExpression IsNot Nothing Then
        If gvSortExpression = e.SortExpression Then
            gvSortDirection = GetSortDirection()
        Else
            gvSortDirection = "ASC"
        End If
        gvSortExpression = e.SortExpression
        gvBasicList.EditIndex = -1
    End If
    Session("listsort") = e.SortExpression
    Session("listsortdirection") = gvSortDirection
    gv.DataSource = GetSortedData(dataTable, e.SortExpression, gvSortDirection)
    gv.DataBind()
End Sub

Answer 1

回发后，GridView的数据源需要再次绑定到网格上才能生效。

以下是我使用的一些示例代码，可能会对您有所帮助：

Protected Sub gridInboxApps_Sorting(sender As Object, e As System.Web.UI.WebControls.GridViewSortEventArgs) Handles gridInboxApps.Sorting

    'must make sure the data is bound before trying to sort, otherwise the grid will contain a null datasource
    BindGridInbox()

    Dim dv As New DataView(gridInboxApps.DataSource)
    dv.Sort = e.SortExpression 'sort direction is attached to grid field

    gridInboxApps.DataSource = dv
    gridInboxApps.DataBind()

    dv.Dispose()

End Sub

你调用的对象是空的。设置数据表时出错

1 个答案: