How to reference a DropDownList inside a DetailsView? - asp.net

Question

I have a DetailsView which contains several text boxes and also a DropDownList.
Now, what I want to do is to write an SelectedIndexChanged event for that DropDownList, but my problem is that I cannot reach it anymore/reference it.
If I just put a DropDownList right on the form it´s no problem but now winds it is inside the DetailsView it seems impossible to reach it.
Any suggestions?
Imports System
Imports System.Web.UI
Imports System.Web.UI.WebControls
Protected Sub DetailsViewAvtaleInfo_PageIndexChanging1(sender As Object, e As DetailsViewPageEventArgs) Handles DetailsViewAvtaleInfo.PageIndexChanging
Dim DropDownListContractType As DropDownList = DirectCast(Me.DetailsViewAvtaleInfo.FindControl("DropDownListContractType"), DropDownList)
Dim TextBoxLeasingPriceMonth As TextBox = DirectCast(Me.DetailsViewAvtaleInfo.FindControl("TextBoxLeasingPriceMonth"), TextBox)
If DropDownListContractType.Text = "Kjøp" Then
TextBoxLeasingPriceMonth.Visible = False
End If
End Sub
I know this is not right, but its as far as I get. I would want to just Write the code within the following sub but it just will not work:
Protected Sub DropDownListContractType_SelectedIndexChanged(sender As Object, e As EventArgs) Handles DropDownListContractType.SelectedIndexChanged
Dim TextBoxLeasingPriceMonth As TextBox = DirectCast(Me.DetailsViewAvtaleInfo.FindControl("TextBoxLeasingPriceMonth"), TextBox)
If DropDownListContractType.Text = "Leasing" Then
TextBoxLeasingPriceMonth.Visible = False
End If
End Sub

Answer 1

You did not post the markup for the dropdownlist, it should be like below (Attached the method to the event):
<asp:DropDownList ID="DropDownListContractType" AutoPostBack="true" runat="server" OnSelectedIndexChanged="DropDownListContractType_SelectedIndexChanged">
<asp:ListItem Text="Kjøp" Value="2"></asp:ListItem>
<asp:ListItem Text="Leasing" Value="1"></asp:ListItem>
</asp:DropDownList>
Your code also have some issues:
Should be DropDownList.SelectedItem.Text instead of
DropDownList.Text.
You have to cast the sender to DropDownList in DropDownListContractType_SelectedIndexChanged method.
You have to find the NamingContainer of DropDownList in DropDownListContractType_SelectedIndexChanged method
If you have the following code, it should work:
Protected Sub DropDownListContractType_SelectedIndexChanged(sender As Object, e As EventArgs)
Dim DropDownListContractType As DropDownList = DirectCast(sender, DropDownList)
Dim TextBoxLeasingPriceMonth As TextBox = DirectCast(DropDownListContractType.NamingContainer.FindControl("TextBoxLeasingPriceMonth"), TextBox)
If DropDownListContractType.SelectedItem.Text = "Leasing" Then
TextBoxLeasingPriceMonth.Visible = False
End If
End Sub
Protected Sub DetailsViewAvtaleInfo_PageIndexChanging(sender As Object, e As DetailsViewPageEventArgs) Handles DetailsViewAvtaleInfo.PageIndexChanging
Dim DropDownListContractType As DropDownList = DirectCast(Me.DetailsViewAvtaleInfo.FindControl("DropDownListContractType"), DropDownList)
Dim TextBoxLeasingPriceMonth As TextBox = DirectCast(Me.DetailsViewAvtaleInfo.FindControl("TextBoxLeasingPriceMonth"), TextBox)
If DropDownListContractType.SelectedItem.Text = "Kjøp" Then
TextBoxLeasingPriceMonth.Visible = False
End If
End Sub
I have tested the code above. If you have any issue, try to copy/paste the markup and code.
You can download my test project to compare with yours here.