Select a ListItem from DropDownList using a Linq Query

Question

I' trying to use a Linq query to find and set the selected value in a drop down list control.

 Dim qry = From i In ddlOutcome.Items _
           Where i.Text.Contains(value)


 Dim selectedItem As ListItem = qry.First

 ddlOutcome.SelectedValue = selectedItem.Value

Even though the documentation says that the DropDownList.Items collection implements IEnumerable I get an error in the Where clause that Option Strict ON disallows late binding!

score 9 · Answer 1 · edited Jun 21 '10 at 22:10

I can give you an answer in C#, and i hope it helps you.

The easiest way it to use the methods of DropDownlist, better than linq query:

DropDownList1.SelectedIndex = 
       DropDownList1.Items.IndexOf(DropDownList1.Items.FindByText("2"));

If you want the linq query it would be like this:

var selected=from i in DropDownList1.Items.Cast<ListItem>()
                     where ((ListItem)i).Text.Contains("2") select i;

DropDownList1.SelectedValue = selected.ToList()[0].Text;

score 6 · Answer 2 · answered Sep 20 '12 at 08:17

6

Anyone thought about:

foreach (ListItem li in drp.Items.Cast<ListItem>().Where(li => li.Value == ""))
{
    li.Selected = true;
}

answered Sep 20 '12 at 08:17

matt_lethargic

2,706
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Excellent! That's exactly what I was thinking of! – dotnetN00b Jan 14 '14 at 15:28

score 2 · Accepted Answer · answered Nov 25 '08 at 14:51

2

Thank you for the suggestions, they were both helpful in leading me to a workable solution. While I agree that using the methods of the drop list itself should be the way to go, I don't have an exact match on the text of the items in the list so I needed another way.

    Dim qry = From i In ddlOutcome.Items.Cast(Of ListItem)() _
              Where i.Text.Contains(value)

    qry.First().Selected = True

The linq query seems preferable to iterating through the list myself, and I learned something in the process.

answered Nov 25 '08 at 14:51

TGnat

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I have reason to use FirstOrDefault in these situations to avoid downstream issues. Check for null! – Allen Oct 31 '15 at 10:43
another answer for reference , it seems `Selected` is same meaning as `Checked` https://stackoverflow.com/questions/18924147/how-to-get-values-of-selected-items-in-checkboxlist-with-foreach-in-asp-net-c – yu yang Jian Jun 13 '17 at 15:52

score 1 · Answer 4 · answered Nov 24 '08 at 23:30

My vb.net is shaky, (c# guy) but try:

Dim qry = From DirectCast(i, ListItem) In ddlOutcome.Items ...

I may have the DirectCast syntax wrong, but you know where I'm coming from. The problem is that at compile time, Items is not verifiable as as a collection of ListItem because IEnumerable's Current property returns Object. Items is not a generic collection.

-Oisin

score 0 · Answer 5 · edited Aug 25 '16 at 17:51

0

simple way to select using following code

foreach (ListItem i in DropDownList1.Items)
   {
      DropDownList1.SelectedValue = i.Value;
     if (DropDownList1.SelectedItem.Text=="text of your DropDownList")
       {
         break;
       }
    }

edited Aug 25 '16 at 17:51

Auguste

2,007
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answered Dec 23 '08 at 12:17

Select a ListItem from DropDownList using a Linq Query

5 Answers5