selection - dependent drop-down in odoo / open erp -

I've made two drop-downs The second dropdown data is dependent on the selected value of the first drop-down.

I have tried many ways, but no relevant solutions were found.

These are my three lists:

  SELECTION_LIST = (('Sela', 'selected A'), ('Selb', 'Selected B')) SELECTION_LIST_2 = ('CELS', 'selected C' And I have defined my fields (selection '1', 'selection1'), ('selection2', 'selection2'), ('selection3', ' Selection 3 '),],' Category 1 ', expected = false),' type_selection_2 ': fields.selection (type_selection = {' selection1 ': [{SELECTION_LIST}],' selection2 ': [{SELECTION_LIST_2}],' selection 3 ': [[SELECTION_LIST_3}],}, "Category 2", required = false)  

Unfortunately I get an error from Try

using the methods-on_change () methods.