How to design the "Next Product"/"Previous Product" button?

Question

Python

Hello!
I would like to ask how you can design a button, by clicking on which it will show the next product from the database - that is, I press the button and the product carousel moves one product back / forward.
I use aiogram

@dp.callback_query_handler(text= 'ххх')
async def name(call: types.CallbackQuery):
    kb = InlineKeyboardMarkup(row_width=2)
    
    cur=con.cursor()
    cur.execute('SELECT Name, Price FROM ххх')
    row=cur.fetchall()
    print(row)

    next =InlineKeyboardButton(text= 'Следующий',callback_data= 'next')
    previous =InlineKeyboardButton(text= 'Предыдущий',callback_data= 'previous')
    add = InlineKeyboardButton(text= 'Добавить в корзину',callback_data= 'add')

    kb.add(next,previous,add)
    await call.message.answer(text= row,reply_markup=kb)

@dp.callback_query_handler(text= 'next')

async def next_button (call: types.CallbackQuery):
   #cur=con.cursor()
   #cur.execute('SELECT Name, Price FROM xxx WHERE Id += 1')
   #row=cur.fetchall()
   #print(row)

Thanks in advance and sorry for the possibly stupid question.

Answer 1

You either need to remember the position of the current user in the product carousel in order to correctly choose which one will be the previous / next / current one to add (as already written above), or use the data of specific products as callback_data buttons.
For example, something like this (items is a dictionary of goods with articles as keys):

#
    numbers = items.keys()
    index_current = numbers.index(number_current)
    if index_current > 0:
        number_prev = numbers[index_current-1]
    else:
        number_prev = numbers[-1]
    if index_current < len(numbers)-1:
        number_next = numbers[index_current+1]
    else:
        number_next = numbers[0]

    next =InlineKeyboardButton(text= 'Следующий',callback_data= f'item:{number_next}')
    previous =InlineKeyboardButton(text= 'Предыдущий',callback_data= f'item:{number_prev}')
    add = InlineKeyboardButton(text= 'Добавить в корзину',callback_data= f'add:{number_current}')

...

    if call.data.startswith('item:'):
       number_current = call.data[5:]
       show_this_item_to_user
    if call.data.startswith('add:'):
       number_current = call.data[4:]
       add_this_item_to_basket