Best way to check if a drop down list contains a value?

user_110233 0
Viewed 171826

When the user navigates to a new page, this ddl's selected index is determined by a cookie, but if the ddl doesn't contain that cookie's value, then I'd like it to be set the 0. What method would I use for the ddl? Is a loop the best way, or is there a simply if statement I can perform?

This is what I've attempted, but it doesn't return a bool.

if ( !ddlCustomerNumber.Items.FindByText( GetCustomerNumberCookie().ToString() ) )
    ddlCustomerNumber.SelectedIndex = 0;
drop-down-menu asp.net c#
10 Answers

There are two methods that come to mind:

You could use Contains like so:

if (ddlCustomerNumber.Items.Contains(new 
    ListItem(GetCustomerNumberCookie().ToString())))
{
    // ... code here
}

or modifying your current strategy:

if (ddlCustomerNumber.Items.FindByText(
    GetCustomerNumberCookie().ToString()) != null)
{
    // ... code here
}

EDIT: There's also a DropDownList.Items.FindByValue that works the same way as FindByText, except it searches based on values instead.

user_988770

That will return an item. Simply change to:

if (ddlCustomerNumber.Items.FindByText( GetCustomerNumberCookie().ToString()) != null)
    ddlCustomerNumber.SelectedIndex = 0;
user_1939390

What about this:

ListItem match = ddlCustomerNumber.Items.FindByText(
    GetCustomerNumberCookie().ToString());
if (match == null)
    ddlCustomerNumber.SelectedIndex = 0;
//else
//    match.Selected = true; // you'll probably select that cookie value
user_1137940

You could try checking to see if this method returns a null: 

if (ddlCustomerNumber.Items.FindByText(GetCustomerNumberCookie().ToString()) != null)
    ddlCustomerNumber.SelectedIndex = 0;
Andy_Rose_17620

If the function return Nothing, you can try this below

if (ddlCustomerNumber.Items.FindByText(
    GetCustomerNumberCookie().ToString()) != Nothing)
{
...
}
user_91907320

Sometimes the value needs to be trimmed of whitespace or it won't be matched, in such case this additional step can be used (source):

if(((DropDownList) myControl1).Items.Cast<ListItem>().Select(i => i.Value.Trim() == ctrl.value.Trim()).FirstOrDefault() != null){}
user_106346380
Related