Library tutorials & articles
Selecting, Confirming & Deleting Multiple Checkbox Items In A DataGrid/GridView - Part 2: Maintaining CheckBox State Acr
By Dimitrios Markatos, published on 20 Jan 2006
Our Main Page
Our main page has pretty much remained the same, the only thing you should notice is simply because we need more data to page through to make this thing work, I have changed the database we're using, field names, SQL query and connection string used in the code from the Pubs database to Northwind.
Main Page
<%@ Page Language="VB" Strict="True" Explicit="True" Buffer="True" Debug="False" Trace="False"
Inherits="MultiDeleteDG.WebForm" Src="mDatagrid.aspx.vb" EnableSessionState="True" %>
<html>
<head></head>
<body>
<form runat="server">
<h3>Selecting, Confirming & Deleting Multiple Checkbox
Items In A DataGrid (i.e. HotMail & Yahoo) -<br>
Part 2: Maintaining CheckBox State Across Pages with Sorting </h3>
<br />
Current Page: <%=MyDataGrid.CurrentPageIndex +1%> <br />
<ASP:DataGrid id="MyDataGrid" runat="server"
Width="700"
BackColor="white"
BorderColor="black"
CellPadding="3"
CellSpacing="0"
Font-Size="9pt"
AutoGenerateColumns="False"
HeaderStyle-BackColor="darkred"
HeaderStyle-ForeColor="white"
AllowPaging="True"
AllowCustomPaging="False"
AllowSorting="True"
OnPageIndexChanged="MyDataGrid_Page"
OnSortCommand="MyDataGrid_Sort"
PageSize="10"
PagerStyle-Mode="NumericPages"
PagerStyle-HorizontalAlign="Right"
DataKeyField="ID">
<Columns>
<asp:TemplateColumn>
<HeaderTemplate>
<asp:CheckBox ID="CheckAll" OnClick="javascript: return select_deselectAll (this.checked, this.id);"
runat="server" />
<font face="Webdings" color="white" size="4">a</font> </HeaderTemplate>
<ItemTemplate>
<asp:CheckBox ID="DeleteThis" OnClick="javascript: return select_deselectAll (this.checked, this.id);"
runat="server" />
</ItemTemplate>
</asp:TemplateColumn>
<asp:BoundColumn HeaderText="StoreID" SortExpression="ID asc" Datafield="ID" runat="server" />
<asp:BoundColumn HeaderText="Store" SortExpression="Company asc" Datafield="Company" runat="server" />
<asp:BoundColumn HeaderText="Address" SortExpression="Address asc" Datafield="Address" runat="server" />
<asp:BoundColumn HeaderText="City" SortExpression="City asc" Datafield="City" runat="server" />
<asp:BoundColumn HeaderText="State" SortExpression="State asc" Datafield="State" runat="server" />
<asp:BoundColumn HeaderText="Zip" SortExpression="Zip asc" Datafield="Zip" runat="server" />
</Columns>
</ASP:DataGrid>
<br />
<asp:Button id="Confirm" onclick="DeleteAllIds" runat="server" Text="Delete Items" />
<asp:Button id="ClearAll" onclick="ClearDataGrid" runat="server" Text="Clear All" />
<span id="OutputMsg" runat="server" EnableViewState="false" />
</form>
</body>
</html>
The Code-Behind
Imports System
Imports System.Collections
Imports System.Data
Imports System.Data.SQLClient
Imports System.Text
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls
Imports Microsoft.VisualBasic Namespace MultiDeleteDG
Public Class WebForm
Inherits System.Web.UI.Page
Protected MyDataGrid As System.Web.UI.WebControls.DataGrid
Protected CheckBox As System.Web.UI.WebControls.CheckBox
Protected OutputMsg As System.Web.UI.HtmlControls.HtmlGenericControl
Protected objConnect As SqlConnection
Protected myDataAdapter As SqlDataAdapter
Protected myCommand As SqlCommand
Protected DS as Dataset
Protected dgItem As DataGridItem
Public deletedIds As String = ""
Public ChkdItems As String = ""
Public SortField As String = ""
Public ChkBxIndex As String = ""
Public BxChkd As Boolean = False
Public CheckedItems As ArrayList
Public Results() As String
Sub Page_PreRender (ByVal Sender As Object, ByVal E As EventArgs)
Dim nl As String = Environment.NewLine
Dim jsScript As New StringBuilder ()
With jsScript
.Append ("<script language=JavaScript>" & nl)
.Append ("<!--" & nl & nl)
.Append ("function confirmDelete (frm) {" & nl & nl)
.Append (" // loop through all elements" & nl & nl)
.Append (" for (i=0; i<frm.length; i++) {"& nl & nl)
.Append (" // Look for our checkboxes only" & nl)
.Append (" if (frm.elements[i].name.indexOf ('DeleteThis') !=-1) {" & nl & nl)
.Append (" // If any are checked then confirm alert, otherwise nothing happens" & nl)
.Append (" if(frm.elements[i].checked) {" & nl & nl)
.Append (" return confirm ('Are you sure you want to delete your selection(s)?')" & nl & nl)
.Append (" }" & nl)
.Append (" }" & nl)
.Append (" }" & nl)
.Append (" }" & nl & nl)
.Append ("/*Using modified select_deselectAll script function of my original one,")
.Append (" from Developerfusion.com forum members - ketcapli & thombo")
.Append (" Forum Post - [http://www.developerfusion.co.uk/forums/topic-22773]*/")
.Append ("function select_deselectAll (chkVal, idVal) {" & nl)
.Append (" var frm = document.forms[0];" & nl)
.Append (" if (idVal.indexOf('DeleteThis') != -1 && chkVal == true){" & nl)
.Append (" var AllAreSelected = true;" & nl)
.Append(" for (i=0; i<frm.length; i++) {" & nl)
.Append(" if (frm.elements[i].id.indexOf('DeleteThis') != -1 && frm.elements[i].checked == false){ " & nl)
.Append (" AllAreSelected = false;" & nl)
.Append (" break;" & nl)
.Append (" } " & nl)
.Append (" } " & nl)
.Append (" if(AllAreSelected == true){" & nl)
.Append (" for (j=0; j<frm.length; j++) {" & nl)
.Append (" if (frm.elements[j].id.indexOf ('CheckAll') != -1) {" & nl)
.Append (" frm.elements[j].checked = true;" & nl)
.Append (" break;" & nl)
.Append (" }" & nl)
.Append (" }" & nl)
.Append (" }" & nl)
.Append (" } else {" & nl)
.Append (" for (i=0; i<frm.length; i++) {" & nl)
.Append (" if (idVal.indexOf ('CheckAll') != -1) {" & nl)
.Append (" if(chkVal == true) {" & nl)
.Append (" frm.elements[i].checked = true; " & nl)
.Append (" } else {" & nl)
.Append (" frm.elements[i].checked = false; " & nl)
.Append (" }" & nl)
.Append (" } else if (idVal.indexOf('DeleteThis') != -1 && frm.elements[i].checked == false) {" & nl)
.Append (" for (j=0; j<frm.length; j++) {" & nl)
.Append (" if (frm.elements[j].id.indexOf ('CheckAll') != -1) { " & nl)
.Append (" frm.elements[j].checked = false;" & nl)
.Append (" break; " & nl)
.Append (" } " & nl)
.Append (" } " & nl)
.Append (" } " & nl)
.Append (" } " & nl)
.Append (" } " & nl)
.Append (" } " & nl & nl)
.Append ("//--> " & nl & nl)
.Append ("</scr" & "ipt>")
End With
RegisterClientScriptBlock ("clientScript", jsScript.ToString())
jsScript = Nothing
Dim button As WebControl = CType(Page.FindControl("Confirm"), WebControl)
button.Attributes.Add("onclick", "return confirmDelete (this.form);")
End Sub
Sub Page_Load (ByVal Sender As Object, ByVal E As EventArgs)
objConnect = New SqlConnection("server=(local);database=Northwind;uid=sa;pwd=;")
If Not IsPostBack Then
Session.Clear()
'Set up default column sorting
If IsNothing(Session ("SortOrder")) Then
BindData ("ID asc")
Else
BindData (Session ("SortOrder"))
End If
End If
End Sub
Sub MyDataGrid_Page (sender As Object, e As DataGridPageChangedEventArgs)
'Get CheckBoxValues before paging occurs
GetCheckBoxValues()
MyDataGrid.CurrentPageIndex = e.NewPageIndex
BindData(Session ("SortOrder"))
'Populate current DataGrid page with the current page items from Session after databind
RePopulateCheckBoxes ()
End Sub
Sub GetCheckBoxValues() 'As paging occurs store checkbox values
CheckedItems = New ArrayList
'Loop through DataGrid Items
For Each dgItem In MyDataGrid.Items
'Retrieve key value of each record based on DataGrids DataKeyField property
ChkBxIndex = MyDataGrid.DataKeys(dgItem.ItemIndex)
CheckBox = dgItem.FindControl("DeleteThis")
'Add ArrayList to Session if it doesnt exist
If Not IsNothing(Session ("CheckedItems")) Then
CheckedItems = Session ("CheckedItems")
End If
If CheckBox.Checked Then
BxChkd = True
'Add to Session if it doesnt already exist
If Not CheckedItems.Contains(ChkBxIndex) Then
CheckedItems.Add(ChkBxIndex.ToString())
End If
Else
'Remove value from Session when unchecked
CheckedItems.Remove(ChkBxIndex.ToString())
End If
Next
'Update Session with the list of checked items
Session ("CheckedItems") = CheckedItems
End Sub
Sub BindData (SortField As String)
'Setup Session Cache for different users
Dim Source As DataView = Session ("dgCache")
If (IsNothing (Source)) Then
Dim sqlQuery As String = "Select OrderId As Id, ShipName As Company," _
& " ShipAddress As Address, ShipCity As City, ShipCountry As State, ShipPostalCode As Zip from Orders"
myDataAdapter = New SqlDataAdapter(sqlQuery, objConnect)
DS = New Dataset()
myDataAdapter.Fill(DS, "MyDataGrid")
'Assign sort expression to Session
Session ("SortOrder") = SortField
'Setup DataView for Sorting
Source = DS.Tables(0).DefaultView
'Insert DataView into Session
Session ("dgCache") = Source
End If
Source.Sort = SortField
MyDataGrid.DataSource = Source
MyDataGrid.DataBind ()
'Close connection
objConnect.Close
End Sub
Sub RePopulateCheckBoxes ()
CheckedItems = New ArrayList
CheckedItems = Session ("CheckedItems")
If Not IsNothing(CheckedItems) Then
'Loop through DataGrid Items
For Each dgItem in MyDataGrid.Items
ChkBxIndex = MyDataGrid.DataKeys(dgItem.ItemIndex)
'Repopulate DataGrid with items found in Session
If CheckedItems.Contains(ChkBxIndex) Then
CheckBox = CType(dgItem.FindControl("DeleteThis"), CheckBox)
CheckBox.Checked = True
End If
Next
End If
'Copy ArrayList to a new array
Results = CheckedItems.ToArray(GetType(String))
'Concatenate ArrayList with comma to properly send for deletion
deletedIds = String.Join(",", Results)
End Sub
Sub DeleteAllIds (ByVal sender As Object, ByVal e As EventArgs)
'Regrab values in case the deletion occurs on the given page and any checkboxes were unchecked
'on the current page without any postback to correct the values in Session
GetCheckBoxValues ()
If BxChkd = True Then
RePopulateCheckBoxes ()
'Delete the rows of data containing the checkbox values
Dim deleteSQL As String = "DELETE from Orders WHERE OrderId IN (" + deletedIds + ");"
myCommand = New SqlCommand (deleteSQL, objConnect)
With myCommand
.Connection.Open()
.ExecuteNonQuery()
End With
'Close connection
objConnect.Close()
OutputMsg.InnerHtml += "<font size=4><b>Store information has been deleted.</b></font>"
OutputMsg.Style("color") = "green"
'Clear all Session values
Session.Clear()
'Reset DataGrid to top
MyDataGrid.CurrentPageIndex = 0
BindData (Session ("SortOrder"))
End If
End Sub
Function SortOrder (Field As String) As String
Dim so As String = Session ("SortOrder")
If Field = so Then
SortOrder = Replace (Field,"asc","desc")
ElseIf Field <> so Then
SortOrder = Replace (Field,"desc","asc")
Else
SortOrder = Replace (Field,"asc","desc")
End If
'Maintain persistent sort order
Session ("SortOrder") = SortOrder
End Function
Sub MyDataGrid_Sort (Sender As Object, E As DataGridSortCommandEventArgs)
'To retain checkbox on sorting
GetCheckBoxValues ()
MyDataGrid.CurrentPageIndex = 0 'To sort from top
BindData (SortOrder (E.SortExpression).ToString()) 'Rebind our DataGrid
'To retain checkbox on sorting
RePopulateCheckBoxes ()
End Sub
Sub ClearDataGrid (ByVal sender As Object, ByVal e As EventArgs)
'Clear All Session Values
Session.Clear()
'Reset DataGrid to top
MyDataGrid.CurrentPageIndex = 0
BindData ("ID asc") 'Rebind our DataGrid
End Sub
End Class
End Namespace
So that being said, let’s now get to the next section where there obviously have been more apparent changes and tweaks, and we’ll now explore these.
Dimitrios, or Jimmy as his friends call him, is a .NET developer/architect who specializes in Microsoft Technologies for creating high-performance and scalable data-driven enterprise Web and deskto...
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hi all,
i faced the same problem, but i have paging in the grid view, so my problem is
when user checks one record in a page and goes to the next page and selects some records there, when he returns to the previous page we need to keep the checked state of whatever records he had checked earlier. When he is finished checking through the pages, he needs a list of records he has checked to delete them form database
iam a new in this forum, i need any one help me as i searched alot and i didn't find any solution
thanks
Hi Dimitrios,
Thanks for such a great tutorial. It works for me. Keep it up.
Oleg
my code under delete button_click event is this
foreach(GridViewRow row in Exp_SummaryGrid.Rows)
{
string cname = row.cells[0].text;
string del = "delete from exp_summary where company=" + cname;
CheckBox cb = (CheckBox)row.Cells[4].Controls[1];
if (cb.Checked==true)
{
SqlCommand delsql = new SqlCommand();
delsql.Connection = conn;
delsql.CommandText = del;
delsql.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(del, conn);
da.DeleteCommand = delsql;
DataSet ds2 = new DataSet();
da.Update(ds2, "exp_summary");
}
}
Hey Thanks! Good suggestions. Now the question remains in getting to those :-) As for .NET 2.0, this article has it already included.
Thanks again!
Having tried your solution I was impressed by the ease with which it worked and it started me thinking of extensions to the principle.
Can I request that you extend the sample code with some additional features?
Firstly add an option to take all the selected records and then insert them into another file. One possible use of this would be to create a shopping 'wish list'.
Secondly to add an update feature. One use of this would be to amend prices of a products in price list, and produce a listing/report before committing the amendments.
Thirdly, add a count of records selected (displayed in the footer?).
And to be really cheeky, can you do it in ASP.NET 2.0 (in case you finish your version before I finish mine) ;-)
Got if figured out. Seems that I inadvertantly had two select_deselectAll routines so it didn't know which to use. Even though in visual studeo it indicates that you cant, via a squiggle under the onclick, have an OnClick event for the asp:Checkbox, you can point it to a javascript routine since that runs only on the client. Also I removed the OnCheckChanged. - john
In net 1.1 how do you get the CheckAll to work? First, I cant use the OnClick since it is not available. Second, if I try to use the OnCheckChanged event I cant point it to the javascript selectdeselectAll routine because it is not a member of 'ASP.mDatagridaspx'. How do you apply events to a datagrid checkbox? Other things are working fine but sure frustrating to not figure this out. - john
Yevgeniy,
No, not at all. No big deal really. We all hope to learn, as I from you as well.:D
Thanks, and equal respect to you.:)
-Jimmy
Well Dimitrios... must admit when you provided those links on StringBuilder vs static concatenation, I just quickly looked through them and was sure that was just another article advocating for static concatenations when the number of strings is known. Now I read it carefully and was surprised and ashamed... It seems like it's me who would be "seeding bad practices" in such a case... Sorry and my respect to you...
No, I appreciate the point you're trying to get across Yevgeniy. At any rate, as I indicated earlier, I agree with you when the concatenation is for minimal strings, but when you are concatenating numerous strings or functions the overhead in instantiation is overall justified I feel, and better practice.
But either way, you're not really going to notice much truly in the way of performance, especially when you apply other performance enhancing techniques, ie, disabling debugging and tracing, closing connections, or even better bind a Datagrid from a Datareader instead of a DataSet for even greater advantages in speed, etc. In .NET, it's the collective means, rather than one tweak, that'll determine a scalable and efficient application.
This applies to looping page size, that in my experience simply displaying a few hundred per page is still ill-advised, and with anything one does in greater magnitude, comes with it degrading performance regardless of much code manipulation.
I meant that instead of
stringBuilder.Append(str1);
stringBuilder.Append(str2);
stringBuilder.Append(str3);
you'd better use
str1 + str2 + str3
That's definitelly gonna be better.
As for looping through form elements, I agree, it raises an issue only on a large amount of form elements. But who knows how large is going to be a particular page in question your readers will be working on.
Yevgeniy,
Thanks for your input, but I would have to disagree on looping through all the elements on the given page being a performance issue, when it's looping through 10 checkboxes per page, not a million. Additionally, utilizing state management via session or viewstate further enhances performance and scalability. So there's no such thing as suboptimal when you perform the task at hand in the manner best suited.
Now regarding your bias using the Stringbuilder class, again I would disagree. First of all, it's good practice in using Stringbuilder as there is performance advantages over static string concatenation - How StringBuilder string concatenation affects performance , string builder vs string concatenation "+" and Use StringBuilder to Build Strings Efficiently. So in my example it’s fine and justified.
I will however give you this though, that I definitely agree with you on not using StringBuilder for 5 lines of code. Incidentally, in Part 1 of my article I did in fact use string concatenation if that makes a difference for you.
But all in all Yevgeniy, I wouldn't just go out and post comments on articles unless you truly have facts to support your claims, which is why the statements you’ve made can "seed a bad practice, especially among newbies."
while thank you very much for this article and other I was lucky to read before, I must admit there are times when you suggest a way to solve a problem in a quite suboptimal way.
It's rarely good to loop through all form elements to find checkboxes appropriate. Well must admit under normal circumstances it can hardly pose a performance hit, but still when number of records is high or the html file is large (which is not good, I know, but I saw times when there seemed to be no other way), it takes a certain amount of time to iterate through all elements. I think it's better to have a client-side array of ids of all checkboxes in question. And on the server side you just emit client side code for each checkbox to register itself with that array. In this case anytime you need to loop through all checkboxes you simply loop through array elements which is much better from performanse standpoint.
Then, I saw how you suggested to create client-side code via a long series of StringBuilder's Append method while it could have been done through static string concatenation. You can seed a bad practice, especially among newbies
No time to write more, gotta be going
Thank you for your articles. Usually, I like them
Yevgeniy
Since I have had this article published here, I have now also been able to implement a way to highlight the selected row or entire set of rows and maintain this state across pages just as in my article, with of course the added benefit of showing users which row(s) they've checked, even when they happen to page back.
To get this going, follow these four steps.
First, add the style properties to the DataGrid:
<SelectedItemStyle BackColor="#F5EDED" ForeColor="Black">
</SelectedItemStyle>
<ItemStyle BackColor="White" ForeColor="Black">
</ItemStyle>
Second, add the highlightChkBxRow(this); JavaScript function call to both checkbox onClick events, so it now becomes:
OnClick="javascript: highlightChkBxRow(this); return select_deselectAll (this.checked, this.id);"
Third, in the code behind - add the following JS function within the Registered Script Block section to handle the client side checkboxes:
.Append ("function highlightChkBxRow(chkbx) {" & nl & nl)
.Append (" if (chkbx.id.indexOf ('DeleteThis') != -1) {" & nl & nl)
.Append (" if (chkbx.checked) {" & nl & nl)
.Append (" chkbx.parentElement.parentElement.style.backgroundColor='#F5EDED';" & nl)
.Append (" chkbx.parentElement.parentElement.style.color='#000000';" & nl)
.Append (" } else {" & nl & nl)
.Append (" chkbx.parentElement.parentElement.style.backgroundColor='#FFFFFF';" & nl)
.Append (" chkbx.parentElement.parentElement.style.color='#000000';" & nl & nl)
.Append (" }" & nl & nl)
.Append (" } else {" & nl & nl)
.Append (" var frm = document.forms[0];" & nl & nl)
.Append (" for (h = 0; h < frm.length; h++) {" & nl & nl)
.Append (" if (frm.elements[h].id.indexOf ('DeleteThis') != -1) {" & nl & nl)
.Append (" if (chkbx.id.indexOf ('CheckAll') != -1 && chkbx.checked) {" & nl & nl)
.Append (" frm.elements[h].parentElement.parentElement.style.backgroundColor='#F5EDED';" & nl)
.Append (" frm.elements[h].parentElement.parentElement.style.color='#000000';" & nl & nl)
.Append (" } else {" & nl & nl)
.Append (" frm.elements[h].parentElement.parentElement.style.backgroundColor='#FFFFFF';" & nl)
.Append (" frm.elements[h].parentElement.parentElement.style.color='#000000';" & nl & nl)
.Append (" }" & nl)
.Append (" }" & nl)
.Append (" } //loop" & nl)
.Append (" }" & nl)
.Append ("}" & nl)
And, finally to maintain our selected rows across pages, replace the RePopulateCheckBoxes () method with the one listed below:
Sub RePopulateCheckBoxes ()
CheckedItems = New ArrayList
CheckedItems = Session ("CheckedItems")
If Not IsNothing(CheckedItems) Then
'Loop through DataGrid Items
For Each dgItem in MyDataGrid.Items
ChkBxIndex = MyDataGrid.DataKeys(dgItem.ItemIndex)
'Repopulate DataGrid with items found in Session
If CheckedItems.Contains(ChkBxIndex) Then
CheckBox = CType(dgItem.FindControl("DeleteThis"), CheckBox)
CheckBox.Checked = True
dgItem.ForeColor = MyDataGrid.SelectedItemStyle.ForeColor
dgItem.BackColor = MyDataGrid.SelectedItemStyle.BackColor
Else
dgItem.ForeColor = MyDataGrid.ItemStyle.ForeColor
dgItem.BackColor = MyDataGrid.ItemStyle.BackColor
End If
Next
End If
'Copy ArrayList to a new array
Results = CheckedItems.ToArray(GetType(String))
'Concatenate ArrayList with comma to properly send for deletion
deletedIds = String.Join(",", Results)
End Sub
And that's it. You're now able to offer the user the added functionality of highlighting the row they've checked or all the rows and persist their selections across pages!
-Jimmy Markatos
This thread is for discussions of Selecting, Confirming & Deleting Multiple Checkbox Items In A DataGrid/GridView - Part 2: Maintaining CheckBox State Acr.