ASP.NET GridView delete confirmation using asp:CommandField

Introduction

There are a few articles out there that already that deals with how to get a JavaScript delete confirmation up in a GridView, I know..., but none of them were exactly what I was after. My method can be used when Updates and Deletes are automatically handled by an asp:LinqDataSource control. You will need your own LINQ DataContext class for your database, and I guess the same principle can be applied to other data source classes too.

Implementation

First, you will need a GridView control that gets its data from a LinqDataSource. Make sure you specify the OnRowDataBound attribute and use the LinqDataSource with delete enabled.

<asp:GridView ID="GridView1" runat="server" PageSize="10" AllowPaging="True" 
    AllowSorting="True" AutoGenerateColumns="False" DataKeyNames="RecordID" 
    DataSourceID="MyDataSource" OnRowDataBound="GridView_RowDataBound">
    <Columns>
        <asp:BoundField DataField="Code" HeaderText="Code" SortExpression="Code" 
                ItemStyle-Width="100px" />
        <asp:BoundField DataField="Description" HeaderText="Description" 
                SortExpression="Description" ItemStyle-Width="560px" 
                ControlStyle-Width="560px" />
        <asp:CommandField HeaderImageUrl="..\Images\DeleteImg.png" ShowDeleteButton="True" 
                DeleteImageUrl="..\Images\DeleteImg.png" DeleteText="Delete Record" 
                ItemStyle-Font-Size="8pt" ItemStyle-Width="30px" ButtonType="Image">
        </asp:CommandField>
    </Columns>
</asp:GridView>
<asp:LinqDataSource ID="MyDataSource" runat="server" 
    ContextTypeName="MyNameSpace.MyDbDataContext" 
    EnableUpdate="true" EnableDelete="true" TableName="MyTable">
</asp:LinqDataSource>

Except for the OnRowDataBound, this control should now work with delete functionality without writing a single line of code.

The next step is to implement the GridView_RowDataBound function which looks like this:

protected void GridView_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        // loop all data rows
        foreach (DataControlFieldCell cell in e.Row.Cells)
        {
           // check all cells in one row
           foreach (Control control in cell.Controls)
           {
                // Must use LinkButton here instead of ImageButton
                // if you are having Links (not images) as the command button.
                ImageButton button = control as ImageButton;
                if (button != null && button.CommandName == "Delete")
                    // Add delete confirmation
                    button.OnClientClick = "if (!confirm('Are you sure " + 
                           "you want to delete this record?')) return;";
            }
        }
    }
}

The important bit here is to use exactly the OnClientClick content provided (except the wording in the message, of course). If you, for example, instead, had "return confirm('Are you sure you want to delete the record')" like many others have suggested, this would mean the Delete command would never be posted back to the server. The actual onclick function call generated/rendered by ASP.NET - if you follow the code supplied above - will be something like this...

onclick="if (!confirm('Are you sure you want to delete this record?')) return;
javascript:__doPostBack('ctl00$cphMain$GridView1','Delete$9')"

You can see that the JavaScript you provide is appended with the postback call from ASP.NET. If you return in your JavaScript prematurely, the postback will never be triggered.

Note: I used images for my command buttons in my GridView. Remember to cast to the LinkButton class instead of the ImageButton class if you use text-links for command buttons.