class SomeSpider(scrapy.Spider):
    name = "some_spider"
    start_urls = [
        'https://<some_site>',
    ]
    def parse(self, response):
        # FIXME: пулучаем все линки на след. страницы
        #        нам нужна ссылка, у которой текст  -- След.
        next_page = ""
        all_links = response.css('div[data-pagination-num="1"] a')
        for a_sel in all_links:
            if a_sel.css('a::text').get() == 'След.':
                next_page = a_sel.css('a::attr(href)').get()
        if next_page:
            yield response.follow(next_page, callback=self.parse_item)
    def parse_item(self, response):

        l = ItemLoader(
            item=TrainItem(),
            response=response
        )

        l.add_css('name','div.product-item-container > div.product-item div.product-item-title > a::text')
        l.add_css('desc', 'div.product-item-container > div.product-item meta[itemprop="description"]::attr(content)')
        l.add_css('cur_price', 'div.product-item-container > div.product-item span.product-item-price-current::text')
        l.add_css('old_price', 'div.product-item-container > div.product-item span.product-item-price-old::text')

        return l.load_item()