Get selected value from combo box in C# WPF

Question

I have just started using WPF forms instead of Windows Forms forms. In a Windows Forms form I could just do:

ComboBox.SelectedValue.toString();

Answer 1

if you want to get the value and validate it you can do something like this

string index = ComboBoxDB.Text;
        if (index.Equals(""))
        {                
            MessageBox.Show("your message");
        }
        else
        {
            openFileDialog1.ShowDialog();
            string file = openFileDialog1.FileName;
            reader = new StreamReader(File.OpenRead(file));
        }