无法使用Selenium和Chrome获取元素文本

Question

I'm trying to scrape Merriam-Webster's Medical Dictionary for medical terms using Python and Chrome as the Selenium webdriver. So far, this is what I have:

    from os import path
    from selenium import webdriver

    # Adding an ad-blocker to Chrome to speed up page load times
    options = webdriver.ChromeOptions()
    options.add_extension(path.abspath("ublock-origin.crx"))

    # Declaring the Selenium webdriver
    driver = webdriver.Chrome(chrome_options = options)

    # Fetching the "A" terms as a test set
    driver.get("https://www.merriam-webster.com/browse/medical/a")

    scraped_words = []  # The list that will hold each word
    page_num = 1
    while page_num < 55:  # There are 54 pages of "A" terms
        try:
            for i in range(4):  # There are 3 columns per page of words
                column = "/html/body/div/div/div[5]/div[2]/div[1]/div/div[3]/ul/li[" + str(i) + "]/a"
                number_of_words = len(driver.find_elements_by_xpath(column))
                for j in range(number_of_words):
                    word = driver.find_elements_by_xpath(column + "[" + str(j) + "]")
                    scraped_words.append(word)
            driver.find_element_by_class_name("fa-angle-right").click()  # Next page
            page_num += 1  # Increment page number to keep track of current page
        except:
            driver.close()

    # Write out words to a file
    with open("medical_terms.dict", "w") as text_file:
        for i in range(len(scraped_words)):
            text_file.write(str(scraped_words[i]))
            text_file.write("\n")

    driver.close()

The above code fetches all the items, as the output of len(scraped_words) is the number expected. However, since I did not specify that I wanted to fetch the text of the elements, I get element identifiers (I think?) instead of text. If I decide to use word = driver.find_elements_by_xpath(column + "[" + str(j) + "]").text in order to specify that I want to get the text of the element, I get the following error:

Traceback (most recent call last):
  File "mw_download.py", line 20, in <module>
    number_of_words = len(driver.find_elements_by_xpath(column))
  File "/usr/local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 325, in find_elements_by_xpath
    return self.find_elements(by=By.XPATH, value=xpath)
  File "/usr/local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 817, in find_elements
    'value': value})['value']
  File "/usr/local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 256, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python3.6/site-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: no such session
  (Driver info: chromedriver=2.31.488774 (7e15618d1bf16df8bf0ecf2914ed1964a387ba0b),platform=Mac OS X 10.12.6 x86_64)


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "mw_download.py", line 27, in <module>
    driver.close()
  File "/usr/local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 541, in close
    self.execute(Command.CLOSE)
  File "/usr/local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 256, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python3.6/site-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: no such session
  (Driver info: chromedriver=2.31.488774 (7e15618d1bf16df8bf0ecf2914ed1964a387ba0b),platform=Mac OS X 10.12.6 x86_64)

What is strange to me here is that the only code I change between runs is on line 22 yet the error message points out line 20 instead.

Any help in deciphering what's going on here and what I can do to fix it would be much appreciated! :+)

Answer 1

You just need to create a words list accessing your elements texts, changing:

word = driver.find_elements_by_xpath(column + "[" + str(j) + "]")

to:

word = [i.text for i in driver.find_elements_by_xpath(column + "[" + str(j) + "]")]

Because .find_elements_by_xpath will always return a list, accessing .text directly won't work.