I can't get my DeleteCommand to work in ASP.net 4.0 VB

Question

I have a ListView that lists features of a product on my website. I included an image button that is supposed to delete the specific feature, but my DeleteCommand won't do it. I have looked in my database, and the record is still there. Is there some code I need to add to the CodeBehind file to get this to work?

  <!-- Features --> 
 <asp:TabPanel id="tab1" class="infoHeader" runat="server" HeaderText="Features" DataKeyNames="MarketingID">
    <HeaderTemplate>Features</HeaderTemplate>
    <ContentTemplate>
        <ul class="info">
        <asp:ListView ID="lvFeatures" runat="server" DataSourceID="dsFeatures">
        <ItemTemplate>
          <li><%#Eval("FeatureTitle")%>
              <asp:ImageButton ID="DeleteFeatureButton" runat="server" Style="float:right;" AlternateText="" ImageUrl="../../images/delete.png" CommandName="Delete" OnCommand="ImageButton1_Command" OnClientClick="return confirm('Are you sure you want to delete this feature?')" />
          </li>
        </ItemTemplate>
        </asp:ListView>
        </ul>
    </ContentTemplate>
</asp:TabPanel>   

   Protected Sub ImageButton1_Command(ByVal sender As Object, ByVal e As CommandEventArgs)
    If TypeOf DirectCast(sender, ImageButton).Parent Is ListViewDataItem Then
        Dim item As ListViewDataItem = TryCast(DirectCast(sender, ImageButton).Parent, ListViewDataItem)
        If item IsNot Nothing Then
            lvFeatures.Items.RemoveAt(item.DisplayIndex)
        End If
    End If
End Sub

<!-- Gets all current features of this product -->
<asp:SqlDataSource ID="dsFeatures" runat="server" 
    ConnectionString="<%$ ConnectionStrings:ProductsConnectionString %>" 
    ProviderName="<%$ ConnectionStrings:ProductsConnectionString.ProviderName %>" 
    SelectCommand="SELECT m.MarketingID, f.FeatureID, f.FeatureTitle FROM Feature f INNER JOIN Marketing m ON m.MarketingData = f.FeatureID WHERE m.MarketingTypeID = 3 and m.ProductID = @ProductID"
    DeleteCommand="DELETE FROM Marketing WHERE MarketingID = @MarketingID">
    <SelectParameters>
        <asp:QueryStringParameter Name="ProductID" QueryStringField="id" />
    </SelectParameters>
    <DeleteParameters>
        <asp:QueryStringParameter Name="MarketingID" QueryStringField="id" />
    </DeleteParameters>
</asp:SqlDataSource>

Answer 1

To delete an item using the SqlDataSource, you have to do it like this:

Change the delete portion of your SqlDataSource control. Remove the QueryStringParameter from the DeleteParameters. You shouldn't have any parameters for the Delete:

<asp:SqlDataSource ID="dsFeatures" runat="server"                 
    ConnectionString="<%$ ConnectionStrings:ProductsConnectionString %>"                 
    ProviderName="<%$ ConnectionStrings:ProductsConnectionString.ProviderName %>"                 
    SelectCommand="SELECT m.MarketingID, f.FeatureID, f.FeatureTitle FROM Feature f INNER JOIN Marketing m ON m.MarketingData = f.FeatureID WHERE m.MarketingTypeID = 3 and m.ProductID = @ProductID"                
    DeleteCommand="DELETE FROM Marketing WHERE MarketingID = @MarketingID">                
    <SelectParameters>                
        <asp:QueryStringParameter Name="ProductID" QueryStringField="id" />                
    </SelectParameters>                               
</asp:SqlDataSource> 

Add MarketingID as a data key to your ListView:

<asp:ListView ID="lvFeatures" runat="server" DataSourceID="dsFeatures" DataKeyNames="MarketingID">    
    <ItemTemplate>    
        <li>    
            <%#Eval("FeatureTitle")%>    
            <asp:ImageButton ID="DeleteFeatureButton" runat="server" Style="float:right;" AlternateText="" ImageUrl="../../images/delete.png" CommandName="Delete" OnClientClick="return confirm('Are you sure you want to delete this feature?');" />        
        </li>    
    </ItemTemplate>    
</asp:ListView> 

To debug the code before the delete occurs, add an OnDeleting event handler to the SqlDataSource control. You can then set a breakpoint before the delete to verify the code that will be executed.

protected void dsFeatures_Deleting(object sender, SqlDataSourceCommandEventArgs e)
{
    string commandText = e.Command.CommandText;
}

Answer 2

You didn't actually assign the command event handler. You should also assign the index to the command argument.

EDIT: Just noticed that the ImageButton is contained in a ListView, which is contained in a TabPanel. Revised code to delete item from ListView.

---

Original method for removing the item from list

<asp:ImageButton ID="ImageButton1" runat="server" CommandName="Delete" CommandArgument='<%#Container.ItemIndex%>' OnCommand="ImageButton1_Command" ...>

In the code behind:

EDIT: Removed c# code and included VB.NET syntax EDIT: Changed method from private to protected

Protected Sub ImageButton1_Command(sender As Object, e As CommandEventArgs)
    If e.CommandName.ToUpper() = "DELETE" Then           
       lvFeatures.Items.RemoveAt(DirectCast(e.CommandArgument, Integer))
    End If
End Sub

EDIT: Added alternative methods for deleting item, because Container.ItemIndex doesn't seem to be working properly in his code

---

Alternative ways of removing the item from the list

Remove the command argument altogether, like this:

<asp:ImageButton ID="ImageButton1" runat="server" CommandName="Delete"  OnCommand="ImageButton1_Command" ...>

Alternative #1: Remove item directly

Protected Sub ImageButton1_Command(sender As Object, e As CommandEventArgs)
    If TypeOf DirectCast(sender, ImageButton).Parent Is ListViewDataItem Then
        Dim item As ListViewDataItem = TryCast(DirectCast(sender, ImageButton).Parent, ListViewDataItem)
        If item IsNot Nothing Then
            lvFeatures.Items.Remove(item)                
        End If
    End If
End Sub

Alternative #2: Remove item at display index

Protected Sub ImageButton1_Command(sender As Object, e As CommandEventArgs)
    If TypeOf DirectCast(sender, ImageButton).Parent Is ListViewDataItem Then
        Dim item As ListViewDataItem = TryCast(DirectCast(sender, ImageButton).Parent, ListViewDataItem)
        If item IsNot Nothing Then                               
            lvFeatures.Items.RemoveAt(item.DisplayIndex)
        End If
    End If
End Sub

Answer 3

If you attach a datakeynames property to the listview it should wire that up for you automatically.

<asp:ListView ID="lvFeatures" runat="server" DataSourceID="dsFeatures"
 DataKeyNames="MarketingID">

This is assuming that the id is part of the data set. You'll have to change the paramter in the <DeleteParameters> to just a regular parameter, not a querystring param.