i want write a script that when i select table name the related column name of the table is show in the drop down in odoo.. here is my code..

table_name = fields.Selection( [('res_partner', 'Contacts'), ('res_company', 'Companies')], string='Table Name', tracking=True, required=True)

column_name = fields.Selection([], string='Column Name')

@api.model
def get_column_names(self, table_name):

query = """
       SELECT column_name
       FROM information_schema.columns
       WHERE table_name = %s
   """
self.env.cr.execute(query, [table_name])
result = self.env.cr.fetchall()
return [(row[0], row[0]) for row in result]


@api.onchange('table_name')
def onchange_table_name(self):
if self.table_name:
    column_names = self.get_column_names(self.table_name)
    columnlist = [(name[0], name[1]) for name in column_names]
    self.column_name.selection = columnlist
    

i am getting following error..

self.column_name.selection = [] AttributeError: 'bool' object has no attribute 'selection'

how to solve this error..