Question

We are trying to update data to the database from an ASP.Net DetailsView with a value from an ASP:DropDownList but when the user clicks the Update button nothing happens. Only the Cancel button will work.

The DropDownList will show the data from the database that was loaded into it but we can’t do an Update.

I’m assuming I’m missing something from the markup coding.

Here’s the markup for the DropDownList:

<asp:TemplateField HeaderText="Class:" SortExpression="ClassID">

    <EditItemTemplate>
        <asp:DropDownList 
            ID="DropDownListClass" 
            Runat="server"
            DataSourceID="SqlDataSourceClasses"
            DataTextField = "ClassName"
            DataValueField="ID"
            AutoPostBack="True" 
            AppendDataBoundItems="true">
        </asp:DropDownList>

        <asp:RequiredFieldValidator ID="RequiredFieldValidatorEditDropDownListClass" runat="server" 
            ControlToValidate="DropDownListClass" 
            ErrorMessage="Please select a class." Font-Bold="True" Font-Italic="True" ForeColor="Red" 
            SetFocusOnError="True" Display="Dynamic">
        </asp:RequiredFieldValidator>
    </EditItemTemplate>

    <ItemTemplate>
        <asp:Literal ID="LiteralClass" runat="server" 
            Text='<%# FormatAsMixedCase(Eval("ClassName").ToString())%>' />
    </ItemTemplate>

    <ItemStyle ForeColor="Blue" />
</asp:TemplateField>

This is the markup of the DataSource which is a simple lookup table:

<asp:SqlDataSource 
    ID="SqlDataSourceClasses" 
    runat="server" 

    ConnectionString="<%$ ConnectionStrings:Islamic Knowledge Academy Staff System %>" 

    SelectCommand="SELECT [ID], [ClassName], [Grade] FROM [Classes]">
</asp:SqlDataSource>

Answer 1

Emad-ud-den,

I think you need a click handler for your submit button so that when the client posts back to the server – it knows to update the database. Something along the lines of:

Sub btnUpdate_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnUpdate.Click

    Dim cnAD As New System.Data.SqlClient.SqlConnection = yourdatasource.getConnection("SqlDataSourceClasses", cnAD)
    Dim cmd As New SqlCommand
    cmd.Connection = cnAd
    cmd.CommandType.Text
    cmd.CommandText = "update yourtable set yourval=@val where yourparams"
    cmd.Paramaters.AddWithValue("@val", DropDownListClass.SelectedValue)
    cmd.ExecuteNonQuery()

End Sub

You could even add a try-catch to get a better idea as to where your code is going awry. Please note that what I’ve written will not work as is, but that it is intended to point you in the right direction.