Initialize Combo box with a blank item

I would like to initialize my combo box with a set of items, the first item should be blank, and this is my code:

private void Form1_Load(object sender, EventArgs e)
{
using (LINQtoEntitiesEntities MyEntities = new LINQtoEntitiesEntities())
{
ObjectQuery Emp = MyEntities.Employee;
//comboBox1.Items.Insert(0, String.Empty);
comboBox1.DataSource = (from u in Emp select new { u.ID, u.LastName }).ToList();
comboBox1.ValueMember = "ID";
comboBox1.DisplayMember = "LastName";
label1.Text = comboBox1.SelectedValue.ToString();
}
}

private void comboBox1_TextChanged(object sender, EventArgs e)
{
if (comboBox1.SelectedIndex.ToString() == "0") return;
using (LINQtoEntitiesEntities MyEntities = new LINQtoEntitiesEntities())
{
ObjectQuery Tsk = MyEntities.TasksPerEmployee;
label1.Text = comboBox1.SelectedValue.ToString();
int val = Convert.ToInt32(comboBox1.SelectedValue.ToString());
comboBox2.DataSource = (from t in Tsk where t.EmployeeID == val select new { t.ID, t.TaskName }).ToList();
comboBox2.ValueMember = "ID";
comboBox2.DisplayMember = "TaskName";
}
}

1 Reply

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Vulpes14y ago
Accepted answer
Your DataSource is a List of anonymous types and so, if you want to insert a blank item at the beginning that needs to be of the same anonymous type.

I'd therefore try replacing this line:

comboBox1.DataSource = (from u in Emp select new { u.ID, u.LastName }).ToList();

with these:

var list = (from u in Emp select new { u.ID, u.LastName }).ToList();
list.Insert(0, new { ID = 0, LastName = "" }); // assuming u.ID is of type int
comboBox1.DataSource = list;

Initialize Combo box with a blank item - LINQ C#