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06.07.04
 By
Sameer Lal
Always wanted to build an easy solution to select multiple items from
an ASP.NET DataGrid and delete them all at once like hotmail does?
Well, it is built in just a few simple steps.
To start with, I am assuming that you are using an Access database
in the backend and know how to populate DataGrid from database in
ASP.NET. If not, look at my other article for beginners "Basics of
Displaying Database Items on Web in ASP.NET" that will be published
soon.
Now, to create a selection checkbox in your data grid, first set up
your data grid as you would do it normally by dragging and dropping
from toolbox in to your webForm1.aspx page. Then right click on data
grid and select property builder. Go to column property tab and add
a template column to the list of selected columns keeping it on the
top of the list. Set the header text value as Select or whatever you
wish. Click OK when you are done. |
Once you are back on your design page, again right click on data grid
and this time you will see another option of edit template column.
Click on to edit template column and drag and drop checkbox control
into ItemTemplate portion and change its ID to “cbSelect” or whatever
name you wish to give it.
When done, right click on it and choose “End Template Editing”. Now,
you will see the difference in your data grid, the first column will
show up as header “Select” and a checkbox in front of each row. Now
drag and drop a “button” above or below the DataGrid, and add a click
event to the button.. You may name the button “Delete Selected”.
Note: My database has key field as SlNo (Serial Number) in tblxyz
which is an auto number field and my delete operation will be based
on this field. You can have some other field as your key field and
you need to modify the codes wherever required.
Now is the important portion, go to html page mode from design mode
and add DataKeyField="SlNo" after < asp:DataGrid id="DataGrid1" and
your code would look something like this:
<body MS_POSITIONING="GridLayout"
bgColor="#ccffff">
<form id="Form1" method="post"
runat="server">
<asp:DataGrid id="DataGrid1"
style="Z-INDEX: 101; LEFT: 8px; POSITION: absolute; TOP: 112px" DataKeyField="SlNo"
runat="server" AutoGenerateColumns="False" Width="464px"
Font-Size="X-Small">
<AlternatingItemStyle BackColor="#99FFFF"></AlternatingItemStyle>
<HeaderStyle HorizontalAlign="Center"
ForeColor="White" BackColor="DarkBlue"></HeaderStyle>
<Columns>
<asp:TemplateColumn HeaderText="Select">
<ItemTemplate>
<asp:CheckBox
id="cbSelected" runat="server"></asp:CheckBox>
</ItemTemplate>
</asp:TemplateColumn>
Now, again back to design view, drag and drop two oledbCommand controls
and type this query in the command text of oleDBCommand1:
DELETE * FROM tblxyz WHERE SlNo =[@SlNo];
In CommandType select Text and in parameters, add a parameter @SlNo
And for oleDBCommand2, type in Command Text as:
SELECT * FROM tblxyz ;
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Now, to code behind page, i.e. in my case, it is webform1.aspx.vb,
add the following code:
Private Sub Button1_Click(ByVal sender
As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim objItem As DataGridItem
For Each objItem In DataGrid1.Items
If objItem.ItemType <> ListItemType.Header And
objItem.ItemType <> ListItemType.Footer And objItem.ItemType <> ListItemType.Pager
Then
Dim ChkSelected1 As Boolean
ChkSelected1 = CType(objItem.Cells(0).FindControl("cbSelected"),
CheckBox).Checked
If ChkSelected1 = True Then
Dim SlNo As Integer
SlNo = DataGrid1.DataKeys(objItem.ItemIndex).ToString()
OleDbCommand1.Parameters("@SlNo").Value = SlNo
OleDbConnection1.Open()
OleDbCommand1.ExecuteNonQuery()
OleDbConnection1.Close()
End If
End If
Next
DataGrid1.EditItemIndex = -1
DataBind1()
Response.Redirect("webform1.aspx")
End Sub
Sub DataBind1()
Dim adp As New OleDb.OleDbDataAdapter(OleDbCommand2)
Dim ds As New DataSet
adp.Fill(ds)
DataGrid1.DataSource = ds
DataGrid1.DataBind()
End Sub
Also, if you want to pop up a confirmation message for deletion, like
in hotmail, you can add the following codes to page_load sub:
Button3.Attributes("onclick") = "return
confirm('Are you sure you _wish to delete these records?');"
And, that is it. You now have a data grid with hotmail style checkboxes
to select multiple records and delete them at once when you click
Delete button.
About the Author:
Sameer Lal is Chartered Accountant from India and Certified Management
Accountant from USA.Sameer is from Toronto, Canada.
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