组合框的C＃代码设置为可选值？

Question

c# code for combobox to set as optional value? I Have 3 Dev Express combo box,I need one combo box as optional how to achieve this?

My code is below:

         if (cmbEmployeeIDName.SelectedItem != null)
            {
                EmployeeId = Convert.ToInt64(cmbEmployeeIDName.SelectedItem.Value);
            }

            if (cmbCompany.SelectedItem != null)
            {
                CompanyId = Convert.ToInt64(cmbCompany.SelectedItem.Value);
            }
            if (cmbDepartment.SelectedItem != null)
            {
                DepartmentId = Convert.ToInt64(cmbDepartment.SelectedItem.Value);
            }

Answer 1

you can compare with empty string

Try this:

if (cmbEmployeeIDName.SelectedItem !=null && cmbEmployeeIDName.SelectedItem.Value.Trim() != "")
{
    EmployeeId = Convert.ToInt64(cmbEmployeeIDName.SelectedItem.Value);
}

Answer 2

First you need to add default value to your Combobox like this

comboBox.Items.Add(" "); 

Then, when you check for assignment:

if (comboBox.SelectedItem != null && comboBox.SelectedItem.Value != " ")
            {
                comboBoxId = Convert.ToInt64(comboBox1.SelectedItem.Value);
            }

And change comboBox to desired comboBox name.

Of course you can change " " for every string you like - just be sure it is unique from real choices