Manually Populating and Selecting ComboBox Items

Question

I can't believe how difficult this simple task is.

I have the following code:

cboCountry.ValueMember = "ID";
cboCountry.DisplayMember = "Title";
var countries = from c in context.Set<sc_Countries>()
                orderby c.Title
                select new { c.ID, c.Title };

Now, I want to populate the ComboBox cboCountry with this collection, and then I want to select the list item with the ID (value) "US".

I was able to add the items to the ComboBox using cboCountry.Items.AddRange(countries.ToList()), but then cboCountry.SelectedValue = "US" had no effect.

Next, I tried adding the collection using cboCountry.DataSource = countries but this just left the control list empty.

Surely there must be a simple way to accomplish this trivial task. Can anyone offer the missing ingredient?

Answer 1

Until you call ToList() on your LINQ statement, you're not actually getting data from the database:

var countries = (from c in context.Set<sc_Countries>()
                 orderby c.Title
                 select new { c.ID, c.Title }).ToList();

Now you should be able to set the DataSource, etc. like you were:

cboCountry.ValueMember = "ID";
cboCountry.DisplayMember = "Title";
cboCountry.DataSource = countries;
cboCountry.SelectedValue = "US"

---

Edit:

Now that I'm re-reading your question, it looks like you were already calling countries.ToList(), but using Items.AddRange. I see the same thing you do when I try it. It appears you have to set the DataSource instead of using Items.AddRange, for SelectedValue to work.