如何在单击另一个下拉列表项时清除GridView？(How to Clear GridView When Clicking Another Dropdownlist Item?)

我有Description和Division DropDownList

当我生成数据时，它将在GridView中显示。当我在Description DropDownList中选择另一个项目时，页面必须清晰但我的问题是，即使我已经在DropDownList中选择了另一个项目，前面数据的GridView仍会显示。

这是我的Page_load代码

受保护的子Page_Load（ByVal sender As Object，ByVal e As System.EventArgs）处理Me.Load userid = IIf（SessionHandler.UserID =“”，User.Identity.Name.ToUpper，SessionHandler.UserID）

If Not IsPostBack Then Description.Items.Clear() If com.isAdmin(com.RetUser_Id(userid)) Then Description.Items.Add(New ListItem("Number Of Part Numbers/Family Input By User", "1")) End If Description.Items.Add(New ListItem("Product Family with No CAS Number", "2")) Description.Items.Add(New ListItem("Product Family with Inactive Exemption", "3")) Description.Items.Add(New ListItem("Part Number Validation", "4")) InitializeSearchOptions() End If ' this conditional statement will not bind the gridview if the sender object is from dropdownlist ' this will avoid unnecessary binding and reduce execution time Dim ctrlname As String = Page.Request.Params.Get("__EVENTTARGET") If ctrlname <> Nothing And ctrlname <> String.Empty Then If Not ctrlname.ToLower.Contains("dropdownlist") And ViewState.Item("Query") <> Nothing Then BindGridview(ViewState.Item("Query")) End If Else For Each ctrl As String In Page.Request.Form Dim c As Control = Page.FindControl(ctrl) If Not TypeOf (c) Is System.Web.UI.WebControls.Button Then If ViewState.Item("Query") <> Nothing Then BindGridview(ViewState.Item("Query")) End If Exit For End If Next Exit Sub End If End Sub

这是我的Description DropDownList的代码

受保护的Sub DescriptionSelectIndexChanged（ByVal sender As Object，ByVal e As System.EventArgs）Handles Description.SelectedIndexChanged InitializeSearchOptions（）End Sub

InitializeSearchOptions代码

Private Sub InitializeSearchOptions() Dim dt As New DataTable Division.Items.Clear() Panel2.Visible = False If Description.Text = "1" Then Division.Items.Add(New ListItem("Select Division", "0")) Division.AutoPostBack = True Username.Items.Clear() Username.Items.Add(New ListItem("Select UserName", "0")) CalendarStyle() MultiView1.ActiveViewIndex = 0 ElseIf Description.Text = "2" Then Division.Items.Add(New ListItem("Select Division", "0")) Division.AutoPostBack = False MultiView1.ActiveViewIndex = 1 ElseIf Description.Text = "3" Then Division.Items.Add(New ListItem("Select Division", "0")) Division.AutoPostBack = False MultiView1.ActiveViewIndex = 2 ElseIf Description.Text = "4" Then Division.AutoPostBack = False Division.Items.Add(New ListItem("Select Division", "0")) MultiView1.ActiveViewIndex = 3 Panel2.Visible = True End If Division.DataSource = GetDivision() Division.DataBind() End Sub

BindGridView代码

Private Sub BindGridview(ByVal query As String) ViewState.Add("Query", query) Dim strBB As String = "" Dim count As Integer = 0 If hiddenDescription.Value = "4" Then DataSource = New DataTable DataSource.Columns.Add(New DataColumn("PART NUMBER", GetType(String))) DataSource.Columns.Add(New DataColumn("IS EXIST?", GetType(String))) DataSource.Columns.Add(New DataColumn("DIVISION NAME", GetType(String))) Dim str() As String = PartNo.Text.Split(vbNewLine) For Each value As String In str If value.Trim = String.Empty Then Continue For End If strBB = "SELECT DISTINCT a.Part_No AS 'PART NUMBER', a.Part_No AS 'IS EXIST?', c.Div_LE_Name AS 'DIVISION NAME' FROM MPartNumber a INNER JOIN MFamily b ON a.Family_Id = b.Family_Id INNER JOIN MDivision c ON b.Div_Id = c.Div_Id WHERE ('" + Division.Text + "' = '0' OR c.Div_Id = '" + Division.Text + "') AND " + IIf(value.Contains("*"), "a.Part_No LIKE '" + value.Trim().Replace("*", "%") + "'", "a.Part_No = '" + value.Trim() + "'") Dim dt As DataTable = dbHelper.GetRecordDT(strBB) Dim i As Integer For i = 0 To dt.Rows.Count - 1 Dim row As DataRow = DataSource.NewRow If dt.Rows.Count > 0 Then row("PART NUMBER") = dt.Rows(i)(0).ToString() row("IS EXIST?") = "YES" row("DIVISION NAME") = dt.Rows(i)(2).ToString() Else row("PART NUMBER") = value.Trim row("IS EXIST?") = "NO" row("DIVISION NAME") = "" End If DataSource.Rows.Add(row) Next Next Else DataSource = dbHelper.GetRecordDT(query) End If count = DataSource.Rows.Count GridView1.DataSource = Nothing GridView1.DataBind() GridView1.PageIndex = 0 GridView1.DataSource = DataSource GridView1.Visible = True GridView1.DataBind() ExportToExcel.Visible = IIf(GridView1.Rows.Count < 1, False, True) Panel1.Visible = IIf(GridView1.Rows.Count < 1, False, True) SetTotalResult(count) End Sub

我试图在gridview中清除Viewstate，但它仍然是相同的。我也试过了autopostback。我在互联网上搜索了不同的解决方案，但我似乎无法解决这个问题。我希望你能帮助我。谢谢。

UPDATE

试过这个

ViewState.Remove("Query")

和

VieState.Clear()

在Page_Load中，每次我在DropDownList中选择另一个项目，但它仍然是相同的。之前成功加载的数据仍然显示。

I have Description and Division DropDownList

When I generate data it will be shown in GridView. When I choose another Item in Description DropDownList the page must be clear but my problem is that the GridView of the previous data still shows even if I choose another Item in the DropDownList already.

Here's my code for Page_load

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load userid = IIf(SessionHandler.UserID = "", User.Identity.Name.ToUpper, SessionHandler.UserID)

Here's my code for Description DropDownList

Protected Sub Description_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Description.SelectedIndexChanged InitializeSearchOptions() End Sub

code for InitializeSearchOptions

Code for BindGridView

I tried to clear the Viewstate in gridview but it's still the same. I also tried the autopostback. I searched different solutions for this in the internet but I can't seem to solve this problem. I hope you can help me with this. Thanks.

UPDATE

Tried this

ViewState.Remove("Query")

and

VieState.Clear()

in Page_Load and every time I select another item in DropDownList but it's still the same. The data that previously loaded successfully still shows.