Adding a Delete Confirmation | RadGrid for ASP.NET AJAX Documentation
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Adding a Delete Confirmation

There are scenarios in which you would like to display a confirmation dialog to prompt the user whether the selected action should be executed or not. There are two possibilities:

On postback invoke the confirm method

In the standard mode, when Telerik RadGrid performs postbacks, you will invoke the confirm javascript method.

You may find useful the RadConfirm dialog integration demo as an example.

Built-in delete confirmation for GridButtonColumn

A common enhancement for GridButtonColumn is to display a confirm dialog when the user presses an arbitrary button from it. The ConfirmText property for GridButtonColumns is especially designed for cases like this. By default, this property value is empty, and no confirmation dialog will be displayed when an action is triggered by clicking on an item in that column. If the developer, however, specifies a confirm text string, the user will be prompted on whether the task should be undertaken.

Built-in delete confirmation for GridButtonColumn with RadWindow

RadGrid also supports showing confirmation dialog with RadWindow. You will need to set the ConfirmDialogType property to RadWindow and place a RadWindowManager on the page. RadGrid will display a RadConfirm dialog.

If there is no RadWindowManager control, RadGrid will ignore this property and will display the default browser confirm dialog.

You can additionally configure the RadWindowManager control.

When ConfirmDialogType is set to "RadWindow" RadGrid allows additional customization—the dialog title can be configured through ConfirmTitle property. The most common usage of this confirmation dialog is upon deleting grid item (note that the Delete column is type of GridButtonColumn).

Display confirmation dialog with text including column cell value

In this case you need to implement a different approach without setting the ConfirmText property for the delete column. You need to have a JavaScript handler for the button that will display the desired confirmation, and you can easily add it as an attribute of the button. For example:

  1. wire the ItemDataBound event of the grid;

  2. extract the text value from the column of your choice;

  3. inside the delete GridButtonColumn, locate the LinkButton control (for the Classic RenderMode or the ElasticButton (for the Lightweight RenderMode).

  4. add onclick attribute to its Attributes collection and relate it to confirm dialog passing the value from the chosen cell and ensuring the event is cancelled if the user does not confirm

<telerik:RadGrid RenderMode="Lightweight" ID="RadGrid1" runat="server" OnItemDataBound="RadGrid1_ItemDataBound">
  <MasterTableView AutoGenerateColumns="False">
    <Columns>
      <telerik:GridBoundColumn HeaderText="ContactName" DataField="ContactName" UniqueName="ContactName">
      </telerik:GridBoundColumn>
      <telerik:GridButtonColumn CommandName="Delete" Text="Delete" UniqueName="DeleteColumn">
      </telerik:GridButtonColumn>
    </Columns>
  </MasterTableView>
</telerik:RadGrid></pre>
private void RadGrid1_ItemDataBound(object sender, Telerik.Web.UI.GridItemEventArgs e)
{
    if (e.Item is GridDataItem)
    {
        GridDataItem dataItem = e.Item as GridDataItem;
        string contactName = dataItem["ContactName"].Text;

        //for the Classic RenderMode
        //LinkButton button = dataItem["DeleteColumn"].Controls[0] as LinkButton;
        //button.Attributes["onclick"] = "return confirm('Are you sure you want to delete " +
        //    contactName + "?')";

        //for the Lightweight RenderMode
        ElasticButton button = dataItem["DeleteColumn"].Controls[0] as ElasticButton
        button.Attributes["onclick"] = "if (!confirm('Are you sure you want to delete " +
            contactName + "?')) {return false;}";
    }
}
Private Sub RadGrid1_ItemDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridItemEventArgs) Handles RadGrid1.ItemDataBound
    If TypeOf e.Item Is GridDataItem Then
        Dim dataItem As GridDataItem = CType(e.Item, GridDataItem)

        Dim contactName As String = dataItem("ContactName").Text

        'For the Classic RenderMode
        'Dim button As LinkButton = CType(dataItem("DeleteColumn").Controls(0), LinkButton)
        'button.Attributes("onclick") = "return confirm('Are you sure you want to delete " & contactName & "?')"

        'for the Lightweight RenderMode
        Dim button As ElasticButton = CType(dataItem("DeleteColumn").Controls(0), ElasticButton)
        button.Attributes("onclick") =  "if (!confirm('Are you sure you want to delete " & contactName & "?')) {return false;}"
    End If
End Sub 'RadGrid1_ItemDataBound

Confirmation from control inside a template

In case you would like to display a confirmation dialog to prompt the user whether the selected action should be executed or not (from control inside some kind of template - ItemTemplate, CommandItemTemplate, etc.), there are two possible scenarios:

  • In the standard mode, when Telerik RadGrid performs postbacks, you will invoke the confirm javascript method.

  • When Telerik RadGrid works in AJAX mode the same approach is still applicable - you merely need to return false from the OnClientClick handler in case the user chooses negative option from the confirmation dialog.

Here is an example usage:

<telerik:RadGrid RenderMode="Lightweight" ID="RadGrid1" runat="server" DataSourceID="AccessDataSource1" OnNeedDataSource="RadGrid1_NeedDataSource">
  <MasterTableView AutoGenerateColumns="False" DataKeyNames="CustomerID" DataSourceID="AccessDataSource1">
    <Columns>
      <telerik:GridBoundColumn DataField="CustomerID" HeaderText="CustomerID" ReadOnly="True"
        SortExpression="CustomerID" UniqueName="CustomerID">
      </telerik:GridBoundColumn>
      <telerik:GridBoundColumn DataField="CompanyName" HeaderText="CompanyName" SortExpression="CompanyName"
        UniqueName="CompanyName">
      </telerik:GridBoundColumn>
      <telerik:GridBoundColumn DataField="ContactName" HeaderText="ContactName" SortExpression="ContactName"
        UniqueName="ContactName">
      </telerik:GridBoundColumn>
      <telerik:GridTemplateColumn UniqueName="TemplateColumn">
        <ItemTemplate>
          <asp:ImageButton ID="ImageButton1" runat="server" AlternateText="Delete Customer"
            OnClientClick="javascript:if(!confirm('This action will delete the selected customer and all of his/her orders. Are you sure?')){return false;}"
            ImageUrl="~/RadControls/Grid/Skins/Default/Delete.gif" />
        </ItemTemplate>
      </telerik:GridTemplateColumn>
    </Columns>
  </MasterTableView>
</telerik:RadGrid>

The following screenshot displays the result from the above code:
Confirmation dialog

tip

You may find useful the RadConfirm dialog integration demo as an example for getting the user confirmation for button clicks.

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