Add this code underneath the import statements on your ‘ArticleEdit’ Form:

categories = [
  (cat['name'], cat) for cat in

This creates a list of 2-tuples:

    ("First category name", <first_row_from_table>),
    ("Final catgegory name", <final_row_from_table>)

The first element of each tuple is what will be displayed in the DropDown box. The second element of the tuple becomes the selected_value property of the DropDown if that option is selected.