在WPF中写入DataGrid的ComboBoxColumnColumn

Question

I would like to have the possibility to write another value which is not in the list in a DatagridComboBoxColumn

How could I do that?

In WinForm I used to do it with

private void DataGridView_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
        {
            ComboBox c = e.Control as ComboBox;
            if (c != null) c.DropDownStyle = ComboBoxStyle.DropDown;
        }
private void DataGridView_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
        {

            if (e.ColumnIndex == dataGridViewTextBox.Index)
            {
                object eFV = e.FormattedValue;
                if (!dataGridViewTextBox.Items.Contains(eFV))
                {

                    DataGridView.Rows[e.RowIndex].Cells[e.ColumnIndex].Value = eFV;


                }
            }
        }

Answer 1

It is possible to use TargetNullValue and FallbackValue :

<DataGrid>
   <DataGridComboBoxColumn ItemsSource="{Binding EmployeeNames,
TargetNullValue='Oops, I am missing',FallbackValue='I am default'}"/>        
</DataGrid>

As MSDN says:

FallbackValue - Gets or sets the value to use when the binding is unable to return a value. TargetNullValue - Gets Gets or sets the value that is used in the target when the value of the source is null.

Update:

ViewModel:

private ObservableCollection<Person> persons;

public ObservableCollection<Person> Persons
{
    get { return persons; }
    set { persons = value;
         OnPropertyChanged("Persons");
    }
}

private void FillData()
{
   persons = new ObservableCollection<Person>();
   for (int i = 0; i < 30; i++)
   {
      if(i%2==0)
         persons.Add(new Person() { IdPerson=i, Name="", SurName="Albahari"});
      else
          persons.Add(new Person() { IdPerson = i, Name = "Ben & Joseph " + i.ToString(), SurName = "Albahari" });
   }
   //If you want set some value, you can do it:
   if(persons[0].Name=="")
      persons[0].Name = "That should be Name";

}