如何检查元素是否存在于 xpath 中，如果不存在则返回空/无值？

Question

I am trying to scrape data from a website given a list of urls which is stored in "data".

I noticed some urls don't have the xpath to "og_price" and "discount" and I get an error of NoSuchElement or just straight saying "og_price" and "discount" is not defined presumably because the certain url doesn't have that xpath.

I want to check if an xpath exists in a url (which I tried to do with try-except) and return a null value or just string "no" but I am stuck on how to do that as I later call ".text" on "og_price" and "discount" which will say 'str' object has no attribue '.text'

for url in data:
    driver.get(url)
    item_name = driver.find_element_by_xpath('//span[@id="productTitle"]')
    brand_name = driver.find_element_by_xpath('//*[@class="a-spacing-small"][.//*[contains(.,"Brand")]]/td[@class="a-span9"]/span')
    price = driver.find_element_by_xpath('//div[@class="a-section a-spacing-micro"]/span[@id="price_inside_buybox"]')
    try: 
        og_price = driver.find_element_by_xpath('//span[@class="priceBlockStrikePriceString a-text-strike"]')
        discount = driver.find_element_by_xpath('//td[@class="a-span12 a-color-price a-size-base priceBlockSavingsString"]')
    except NoSuchElementException:
        og_price = null
        discount = null
    

    row = { 'Item Name': item_name.text,
            'Brand Name': brand_name.text,
            'Price': price.text,
            'Original Price': og_price.text,
            'URL': url
          }

Answer 1

@Harry Kim the proper way of checking if a element exists is by wraping the check in the try/catch block as you did above. To resolve the issue of null object exception, you can have a if check before assigning the element to the row map. Something like,

    try: 
        og_price = driver.find_element_by_xpath('//span[@class="priceBlockStrikePriceString a-text-strike"]')
        discount = driver.find_element_by_xpath('//td[@class="a-span12 a-color-price a-size-base priceBlockSavingsString"]')
    except NoSuchElementException:
        og_price = None
        discount = None
    

    row = { 'Item Name': item_name.text,
            'Brand Name': brand_name.text,
            'Price': price.text,
            'URL': url
          }
    if og_price is not None:
          row["Original Price"] = og_price.text
    else:
          row["Original Price"] = "N/A"

Also it is a good idea to use function like find_element_by_css_selector or find_element_by_id if you have a well defined css label. We go for Xpath only when the target element does have a proper id or css label.