Clear out a DropDownList via looping through controls

Question

I am trying to loop through every control in a panel and clear out all the contents if it is a DropDownList.

Here is what I have :

private void ClearOut()
{
    foreach (Control list in MainPanel.Controls)
    {
        if (list.ToString().Equals("System.Web.UI.WebControls.DropDownList"))
        {
            //Clear it out here
        }
    }
}

This code does find every DropDownList, but then I cannot figure out how to clear them out once I get there. I can't use any properties of a DropDownList like selectedindex or items.clear().

abatishchev · Accepted Answer · 2013-04-10T00:46:08.677

2

using System.Linq;
using System.Web.UI.WebControls;

foreach (DropDownList list in MainPanel.Controls.OfType<DropDownList>())
{
    list.Items.Clear();
}

or the same but manually:

foreach (Control c in MainPanel.Controls)
{
    DropDownList list = c as DropDownList;
    if (list != null)
    {
        list.Items.Clear();
    }
}

edited Apr 10 '13 at 00:46

answered Apr 09 '13 at 18:00

abatishchev

98,240
88
296
433

Good soln, you would also need () at the end of OfType – Jason Renaldo Apr 09 '13 at 18:13

score 1 · Answer 2 · answered Apr 09 '13 at 18:01

1

Use this:

if(list is DropDownList)
{
DropDownList DDL = list as DropDownList;
DDL.Items.Clear();
}

answered Apr 09 '13 at 18:01

Shaharyar

12,254
4
46
66

[Still it's better to do not mix operators `as` and `is`](http://stackoverflow.com/questions/496096/casting-vs-using-the-as-keyword-in-the-clr) – abatishchev Apr 09 '13 at 18:13

Clear out a DropDownList via looping through controls

2 Answers2