Best way to check if a drop down list contains a v

2019-02-01 15:43发布

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;

9条回答
老娘就宠你
2楼-- · 2019-02-01 16:37

//you can use the ? operator instead of if

ddlCustomerNumber.SelectedValue = ddlType.Items.FindByValue(GetCustomerNumberCookie().ToString()) != null ? GetCustomerNumberCookie().ToString() : "0";
查看更多
我想做一个坏孩纸
3楼-- · 2019-02-01 16:44

That will return an item. Simply change to:

if (ddlCustomerNumber.Items.FindByText( GetCustomerNumberCookie().ToString()) != null)
    ddlCustomerNumber.SelectedIndex = 0;
查看更多
啃猪蹄的小仙女
4楼-- · 2019-02-01 16:45

On C# this works:

        if (DDLAlmacen.Items.Count > 0)
        {
            if (DDLAlmacen.Items.FindByValue("AlmacenDefectoAndes").Value == "AlmacenDefectoAndes")
            {
                DDLAlmacen.SelectedValue = "AlmacenDefectoAndes";
            }
        }

Update:

Translating the code above to Visual Basic doesn't work. It throws "System.NullReferenceException: Object reference not set to an instance of an object.."

So. for this to work on Visual Basic, I had to change the code like this:

        If DDLAlmacen.Items.Count > 0 Then
            If DDLAlmacen.Items.Contains(New ListItem("AlmacenDefectoAndes")) Then
                DDLAlmacen.SelectedValue = "AlmacenDefectoAndes"
            End If
        End If
查看更多
登录 后发表回答