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Last post Dec 28, 2016 09:52 AM by Zhi Lv - MSFT

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kaiclassic

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228 Posts

GridView - Preserve checkbox status after paging - no direct calling DataBind()

Dec 27, 2016 08:34 AM|kaiclassic|LINK

Dear all,

Sorry it may sound impolite, but please read the post before posting those modal answer. My problem may be different than those modal answer.

I have struggled with this for sometime. Please help.

I have a pretty standard page. At top there are some filters that user can select to reduce the number of resulting rows (like changing the data from and date to.) In the middle there are two buttons. One is to query the database again, but with filtering at top. The second button is to print selected row. So the GridView following has checkbox as the first column. it also has paging enabled. There is a SqlDataSource at the bottom which GridView's DataSourceID is pointing to.

I find out the GridView does not keep track of which rows has been ticked after paging. I search the web and find Preserving state of Checkboxes while paging in ASP.Net GridView Control. This involves calling GridView1.DataBind() directly. As my understanding, if GridView's DataSourceID is specified, the DataBind() occurs automatically. So whenever there is an explicit call to DataBind(), I remove it. However the rechecking (re-ticking) the checkbox does not appear. I step through the code, but the page just does not show it.

If I add back the DataBind() statement, the check disappears immediately after I click on it!

Question: How do I get the GridView to keep track of checkboxes that I have ticked? Please note

I want to keep it simple. So I don't want to fill in a System.Data.DataTable first before binding to GridView. (I have searched the web and all suggest this way! :( )
When the page is first shown, there is a query to the database, but the resulting rows is zero (0). (Don't know if this helps.) User have to adjust the data from to Today - 4 months, press Query button to get some rows.
I do not have 'Check All' mechanism.

Here is the source code:

Imports System
Imports System.Collections

Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim startData As Date = Date.Today.AddMonths(-1)
        Dim buildQueryString As String = String.Empty
        Dim checkBoxArray As ArrayList
        Dim chk As CheckBox
        Dim checkBoxIndex As Integer

        If Not IsPostBack() Then
            txtSDOCDate.Text = startData.ToString("yyyyMMdd")
            txtEDOCDate.Text = Date.Today.ToString("yyyyMMdd")

            'set SQL string
            ds001DocList.SelectCommand = "SELECT * FROM [vWEB001_DocList] " _
                & "WHERE ([UsrID] = '" & Session("UsrID") & "') " _
                & "AND DOC_DATE >= '" & txtSDOCDate.Text & "' " _
                & "AND DOC_DATE <= '" & txtEDOCDate.Text & "' " _
                & "ORDER BY [DOC_DATE] DESC, [DOC_ID] DESC"
        Else
            getQuery(buildQueryString)
            ds001DocList.SelectCommand = buildQueryString

            ' From ASP Snippets
            If ViewState("checkBoxArray") IsNot Nothing Then
                checkBoxArray = DirectCast(ViewState("checkBoxArray"), ArrayList)
            Else
                checkBoxArray = New ArrayList()
            End If

            ' Preserve check box state
            For i As Integer = 0 To gvQuery.Rows.Count - 1
                If gvQuery.Rows(i).RowType = DataControlRowType.DataRow Then
                    chk = DirectCast(gvQuery.Rows(i).Cells(0).FindControl("cbSelectRow"), CheckBox)
                    checkBoxIndex = gvQuery.PageSize * gvQuery.PageIndex + (i + 1)

                    If chk.Checked Then
                        If checkBoxArray.IndexOf(checkBoxIndex) = -1 Then
                            checkBoxArray.Add(checkBoxIndex)
                        End If
                    Else
                        If checkBoxArray.IndexOf(checkBoxIndex) <> -1 Then
                            checkBoxArray.Remove(checkBoxIndex)
                        End If
                    End If
                End If
            Next
            ViewState("checkBoxArray") = checkBoxArray
        End If
        ' Force to DataBind()
        gvQuery.DataBind()  ' *** If I have this, the checkbox disappears immdiately
    End Sub

    Private Sub getQuery(ByRef queryString As String)
        queryString = "SELECT * FROM [vWEB001_DocList] " _
                & "WHERE ([UsrID] = '" & Session("UsrID") & "') "

        ' Document #
        If txtDocID.Text <> String.Empty Then
            queryString &= "AND DOC_ID LIKE " & txtDocID.Text.Trim() & "%' "
        End If
        ' Document Date
        If txtSDOCDate.Text <> String.Empty Then
            queryString &= "AND DOC_DATE >= '" & txtSDOCDate.Text & "' "
        End If
        If txtEDOCDate.Text <> String.Empty Then
            queryString &= "AND DOC_DATE <= '" & txtEDOCDate.Text & "' "
        End If
		
		' Other type of filtering
    End Sub

    Protected Sub btnQuery_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnQuery.Click
        Dim buildNewQuery As String = String.Empty

        getQuery(buildNewQuery)
        ' Run query
        ds001DocList.SelectCommand = buildNewQuery
        gvQuery.DataBind()
        ' Take care the index as well
        gvQuery.PageIndex = 0
    End Sub

    Protected Sub gvQuery_PageIndexChanging(ByVal sender As Object, _
                  ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) _
                  Handles gvQuery.PageIndexChanging
        gvQuery.PageIndex = e.NewPageIndex

        Dim checkBoxArray As ArrayList
        Dim chk As CheckBox
        Dim checkBoxIndex As Integer

        If ViewState("checkBoxArray") IsNot Nothing Then
            checkBoxArray = DirectCast(ViewState("checkBoxArray"), ArrayList)

            For i As Integer = 0 To gvQuery.Rows.Count - 1
                If gvQuery.Rows(i).RowType = DataControlRowType.DataRow Then
                    chk = DirectCast(gvQuery.Rows(i).Cells(0).FindControl("cbSelectRow"), CheckBox)
                    checkBoxIndex = (gvQuery.PageSize * gvQuery.PageIndex) + (i + 1)

                    If checkBoxArray.IndexOf(checkBoxIndex) <> -1 Then
                        chk.Checked = True
                    End If
                End If
            Next
        End If
    End Sub
End Class

Please click 'Mark as Answer' if my reply has assisted you

Zhi Lv - MSF...

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Re: GridView - Preserve checkbox status after paging - no direct calling DataBind()

Dec 28, 2016 09:52 AM|Zhi Lv - MSFT|LINK

Hi kaiclassic,

kaiclassic
How do I get the GridView to keep track of checkboxes that I have ticked? Please note

Please set ds001DocList as datasource of gvQuery after you set the SelectCommand in method, such as btnQuery_Click() and gvQuery_PageIndexChanging()

It can fix your paging problem.

I have modified your code. Now it can keep the track of the rows.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim startData As Date = Date.Today.AddMonths(-1)
        Dim buildQueryString As String = String.Empty
        Dim checkBoxArray As ArrayList
        Dim chk As CheckBox
        Dim checkBoxIndex As Integer


        If ViewState("checkBoxArray") IsNot Nothing Then
            checkBoxArray = DirectCast(ViewState("checkBoxArray"), ArrayList)
        Else
            checkBoxArray = New ArrayList()
        End If
        If Not IsPostBack() Then
            txtSDOCDate.Text = startData.ToString("yyyyMMdd")
            txtEDOCDate.Text = Date.Today.ToString("yyyyMMdd")


            ds001DocList.SelectCommand = "SELECT * FROM [vWEB001_DocList] " _
                & "WHERE ([UsrID] = '" & Session("UsrID") & "') " _
                & "AND DOC_DATE >= '" & txtSDOCDate.Text & "' " _
                & "AND DOC_DATE <= '" & txtEDOCDate.Text & "' " _
                & "ORDER BY [DOC_DATE] DESC, [DOC_ID] DESC"
            gvQuery.DataSource = ds001DocList          
            gvQuery.DataBind()

        Else
            For i As Integer = 0 To gvQuery.Rows.Count - 1
                If gvQuery.Rows(i).RowType = DataControlRowType.DataRow Then
                    chk = DirectCast(gvQuery.Rows(i).Cells(0).FindControl("cbSelectRow"), CheckBox)
                    checkBoxIndex = gvQuery.PageSize * gvQuery.PageIndex + (i + 1)
                    If chk.Checked Then
                        If checkBoxArray.IndexOf(checkBoxIndex) = -1 Then
                            checkBoxArray.Add(checkBoxIndex)
                        End If
                    Else
                        If checkBoxArray.IndexOf(checkBoxIndex) <> -1 Then
                            checkBoxArray.Remove(checkBoxIndex)
                        End If
                    End If
                End If
            Next
            ViewState("checkBoxArray") = checkBoxArray
        End If
    End Sub


    Private Sub getQuery(ByRef queryString As String)
        queryString = "SELECT * FROM [vWEB001_DocList] " _
                & "WHERE ([UsrID] = '" & Session("UsrID") & "') "
        'Document #
        If txtDocID.Text <> String.Empty Then
            queryString &= "AND DOC_ID LIKE " & txtDocID.Text.Trim() & "%' "
        End If
        'Document Date
        If txtSDOCDate.Text <> String.Empty Then
            queryString &= "AND DOC_DATE >= '" & txtSDOCDate.Text & "' "
        End If
        If txtEDOCDate.Text <> String.Empty Then
            queryString &= "AND DOC_DATE <= '" & txtEDOCDate.Text & "' "
        End If

    End Sub

    Protected Sub btnQuery_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnQuery.Click
        Dim buildNewQuery As String = String.Empty

        getQuery(buildNewQuery)
        ds001DocList.SelectCommand = buildNewQuery
        gvQuery.DataSource = ds001DocList
        gvQuery.PageIndex = 0
        gvQuery.DataBind()
    End Sub

    Protected Sub gvQuery_PageIndexChanging(ByVal sender As Object,
                  ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) _
                  Handles gvQuery.PageIndexChanging

        Dim buildNewQuery As String = String.Empty
        getQuery(buildNewQuery)
        ds001DocList.SelectCommand = buildNewQuery
        gvQuery.DataSource = ds001DocList
        gvQuery.PageIndex = e.NewPageIndex
        gvQuery.DataBind()

        Dim checkBoxArray As ArrayList
        Dim chk As CheckBox
        Dim checkBoxIndex As Integer

        If ViewState("checkBoxArray") IsNot Nothing Then
            checkBoxArray = DirectCast(ViewState("checkBoxArray"), ArrayList)

            For i As Integer = 0 To gvQuery.Rows.Count - 1
                If gvQuery.Rows(i).RowType = DataControlRowType.DataRow Then
                    chk = DirectCast(gvQuery.Rows(i).Cells(0).FindControl("cbSelectRow"), CheckBox)
                    checkBoxIndex = (gvQuery.PageSize * gvQuery.PageIndex) + (i + 1)

                    If checkBoxArray.IndexOf(checkBoxIndex) <> -1 Then
                        chk.Checked = True
                    End If
                End If
            Next
        End If
    End Sub

Besides, here is an article about Preserving state of Checkboxes while paging in ASP.Net GridView Control. You could check it.

Best regards,
Dillion

MSDN Community Support
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