Preselecting item in Razor ListBox

Tuesday, May 27, 2014 by Nate Bross

Someone asked on Stack Overflow:

I have a database, that contains an tinyint column with “1” or “0” for marking as “yes” or “no”.

In my razor view I want to Show this in a ListBox. When reading rows out of the database, I want to preselect the corresonding item in the ListBox.

Code here is simplified:

var mItems = new List<SelectListItem>{
    new SelectListItem { Value="1", Text="Yes"},
    new SelectListItem { Value="0", Text="No"}
};

int mIsProofed = 0;

// This doesn´t preselect my item:
mItems.Select(x => x.Value == mIsProofed.ToString());

:

@Html.ListBox("mylistbox", mItems)

Any ideas how to resolve this?

I posted the following answer, which was chosen as the accepted answer and received 2 upvotes:

You need to set the Selected property on the SelectListItem.

I’d update your code to be similar to this:

var selectedItem = mItems.FirstOrDefault(x => x.Value == mIsProofed.ToString());
if(selectedItem != null) 
{
     selectedItem.Selected = true;
}

This will find the item you wish to select, and update its selected property if it is found, otherwise it does not modify anything.

The .Select() method you are using is used to perform a projection on the list, in other words it is more like the select command in SQL, where you specify a subset (or the full set) of data.

Originally posted on Stack Overflow — 2 upvotes (accepted answer). Licensed under CC BY-SA.