What ways can I present an addtional field to combobox when user can't find item they looking for?

Question

I have ComboBox and it has item inside user can select item they want, if they can't find item they can select first item (Not in this list) and input data in textbox (textbox will show if user select first item)

(Not in this list)
Item A
Item B
Item C

Now my boss just email me that they think this is not convenient for them and need me to create more easy-to-use UI. Please help me how to improve my UI?

Answer 1

One way of doing this is to have radio buttons:

* Existing Item

   | Choose item combobox         | 

* New Item

   | Text field to make new item  |

You'd disable the the combo box when selecting "New Item" and vice versa.

You could also compact this down to

* Existing Item      * New Item

    | Combo box OR Text field depending on what's selected |

As with all UX/UI design, do a quick and dirty usability test before deciding.

Answer 2

Did you see how GMail solved it? I think it's pretty elegant and efficient to use:

No selection / text input:

Text input without match (creates new label on enter):

Answer 3

Another option would be to just simply add a "Add" or "New [Type]" link next to the dropdown... this would ideally open a modal window with a form for the item's attributes (if there's more than one, otherwise the window's probably not needed), and once saved, close the window, refresh the dropdown, and select the new item.