WPF ComboBox with IsEditable=“True” - How can I indicate that no match was found?

Question

Using the following simple text box as an example:

    Angus/ComboBoxItem         


        

Answer 1

This is a good solution until you have a lot of records in the combo box. I would do it this way:

Declare this at the top of the file

List items = new List(); 

private void myComboBox_KeyUp(object sender, KeyEventArgs e) 
{ 
  TextBox textBox = myComboBox.Template.FindName("PART_EditableTextBox", myComboBox) as TextBox; 

     // indicates whether the new character added should be removed 
    bool shouldRemove = true; 

    // this way you don't fill the list for every char typed
    if(items.Count <= 0)
    { 
       for (int i = 0; i < myComboBox.Items.Count; i++) 
       { 
           items.Add(((ComboBoxItem)myComboBox.Items.GetItemAt(i)).Content.ToString()); 
       } 
    }
    // then look in the list
    for (int i = 0; i < items.Count; i++) 
    { 
        // legal character input 
        if(textBox.Text != "" && items.ElementAt(i).StartsWith(textBox.Text)) 
        { 
            shouldRemove = false; 
            break; 
        } 
    } 

    // illegal character input 
    if (textBox.Text != "" && shouldRemove) 
    { 
        textBox.Text = textBox.Text.Remove(textBox.Text.Length - 1); 
        textBox.CaretIndex = textBox.Text.Length; 
    } 
} 

unless the binding is continue adding records to the combo box, I think is a more efficient lookup