test.py

    def test(self):
        a_list = []
        for row in range(self.orders_table.rowCount()):
            for col in range(self.orders_table.columnCount()):
                if self.orders_table.item(row, col) == None:
                    value = '0'
                else:
                    value = self.orders_table.item(row, col).text()
                a_list.append(value)
        print(a_list)