How to select only divs with specific children span with xpath python - python-3.x

Question

I am currently trying to scrap information of a particular ecommerce site and i only want to get product information like product name, price, color and sizes of only products whose prices have been slashed.
i am currently using xpath
this is my python scraping code
from lxml import html
import requests
class CategoryCrawler(object):
def __init__(self, starting_url):
self.starting_url = starting_url
self.items = set()
def __str__(self):
return('All Items:', self.items)
def crawl(self):
self.get_item_from_link(self.starting_url)
return
def get_item_from_link(self, link):
start_page = requests.get(link)
tree = html.fromstring(start_page.text)
names = tree.xpath('//span[#class="name"][#dir="ltr"]/text()')
print(names)
Note this is not the original URL
crawler = CategoryCrawler('https://www.myfavoriteecommercesite.com/')
crawler.crawl()
When the program is Run ... These are the HTML Content Gotten from the E-commerce Site
Div of Products With Price Slash
div class="products-info">
<h2 class="title"><span class="brand ">Apple </span> <span class="name" dir="ltr">IPhone X 5.8-Inch HD (3GB,64GB ROM) IOS 11, 12MP + 7MP 4G Smartphone - Silver</span></h2>
<div class="price-container clearfix">
<span class="sale-flag-percent">-22%</span>
<span class="price-box ri">
<span class="price ">
<span data-currency-iso="NGN">₦</span>
<span dir="ltr" data-price="388990">388,990</span>
</span>
<span class="price -old ">
<span data-currency-iso="NGN">₦</span>
<span dir="ltr" data-price="500000">500,000</span>
</span>
</span>
</div>
div
Div of Products with No Price Slash
div class="products-info">
<h2 class="title"><span class="brand ">Apple </span> <span class="name" dir="ltr">IPhone X 5.8-Inch HD (3GB,64GB ROM) IOS 11, 12MP + 7MP 4G Smartphone - Silver</span></h2>
<div class="price-container clearfix">
<span class="price-box ri">
<span class="price ">
<span data-currency-iso="NGN">₦</span>
<span dir="ltr" data-price="388990">388,990</span>
</span>
</span>
</div>
div
Now this is my exact Question
i want to know how to select only the parent divs i.e
div class="price-container clearfix"> that also contains any of these children span classes
span class="price -old "> or
span class="sale-flag-percent">
Thank you all

Answer 1

One solution would be get all <div class="price-container clearfix"> and iterate, checking with the string of the whole element that your keywords exist.
But a better solution would be to use conditionals with xpath:
from lxml import html
htmlst = 'your html'
tree=html.fromstring(htmlst)
divs = tree.xpath('//div[#class="price-container clearfix" and .//span[#class = "price -old " or #class = "sale-flag-percent"] ]')
print(divs)
This get all divs where class="price-container clearfix" and then check if contains span with the searched classes.