Re: Find if value exists in drop down

[Ken Cox [Microsoft MVP]]

Hi Matt,

One way is to use the FindByText method of the ddl. It looks through the
items and tries to find a match (case-sensitive).

If the item is Nothing, there's no match. If it returns an object, you've
found what you were after. Here's some code that shows what I mean:


Private Sub Button1_Click _
(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button1.Click
Dim lstItem As ListItem
lstItem = DropDownList1.Items.FindByText _
(TextBox1.Text)
If IsNothing(lstItem) Then
Label1.Text = "Not Found"
Else
Label1.Text = "Found"
End If
End Sub

<form id="Form1" method="post" runat="server">
<P>
<aspropDownList id="DropDownList1" runat="server">
<asp:ListItem Value="Red">Red</asp:ListItem>
<asp:ListItem Value="Green">Green</asp:ListItem>
<asp:ListItem Value="Blue">Blue</asp:ListItem>
</aspropDownList></P>
<P>
<asp:TextBox id="TextBox1" runat="server">Yellow</asp:TextBox></P>
<P>
<asp:Label id="Label1" runat="server">Label</asp:Label></P>
<P>
<asp:Button id="Button1" runat="server" Text="Find"></asp:Button></P>
</form>

Does this help?

Ken
Microsoft MVP [ASP.NET]

 

[MattB]

Thanks! I think so, but before I could implement it the client changed their
minds about that feature so it no longer applies. I've filed it for future
reference and will give it a show when (if?) I have time.

Matt

Hi Matt,

One way is to use the FindByText method of the ddl. It looks through
the items and tries to find a match (case-sensitive).

If the item is Nothing, there's no match. If it returns an object,
you've found what you were after. Here's some code that shows what I
mean:


Private Sub Button1_Click _
(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button1.Click
Dim lstItem As ListItem
lstItem = DropDownList1.Items.FindByText _
(TextBox1.Text)
If IsNothing(lstItem) Then
Label1.Text = "Not Found"
Else
Label1.Text = "Found"
End If
End Sub

<form id="Form1" method="post" runat="server">
<P>
<aspropDownList id="DropDownList1" runat="server">
<asp:ListItem Value="Red">Red</asp:ListItem>
<asp:ListItem Value="Green">Green</asp:ListItem>
<asp:ListItem Value="Blue">Blue</asp:ListItem>
</aspropDownList></P>
<P>
<asp:TextBox id="TextBox1" runat="server">Yellow</asp:TextBox></P>
<P>
<asp:Label id="Label1" runat="server">Label</asp:Label></P>
<P>
<asp:Button id="Button1" runat="server"
Text="Find"></asp:Button></P> </form>

Does this help?

Ken
Microsoft MVP [ASP.NET]

I have some drop-down lists I'd like to pre-populate from values
in a database. I've found that if I just blindly assign the
SelectedValue, I run
into problems if what I'm trying to assign isn't a choice for that
dropdown.
So what I need to know, is how do I test for the existence of a
value in
a dropdown list? Seems like it should be easy, but I haven't been
able to make it work yet.

Thanks!

Matt