crawl site that has infinite scrolling using pytho

问题:

I have been doing research and so far I found out the python package that I will plan on using its scrapy, now I am trying to find out what is a good way to build a scraper using scrapy to crawl site with infinite scrolling. After digging around I found out that there is a package call selenium and it has python module. I have a feeling someone has already done that using Scrapy and Selenium to scrape site with infinite scrolling. It would be great if someone can point towards to an example.

回答1:

from selenium.webdriver.common.keys import Keys
import selenium.webdriver
driver = selenium.webdriver.Firefox()
driver.get("http://www.something.com")
lastElement = driver.find_elements_by_id("someId")[-1]
lastElement.send_keys(Keys.NULL)

This will open a page, find the bottom-most element with the given id and the scroll that element into view. You'll have to keep querying the driver to get the last element as the page loads more, and I've found this to be pretty slow as pages get large. The time is dominated by the call to driver.find_element_* because I don't know of a way to explicitly query the last element in the page.

Through experimentation you might find there is an upper limit to the amount of elements the page loads dynamically, and it would be best if you wrote something that loaded that number and only then made a call to driver.find_element_*.

回答2:

You can use selenium to scrap the infinite scrolling website like twitter or facebook.

Step 1 : Install Selenium using pip

pip install selenium 

Step 2 : use the code below to automate infinite scroll and extract the source code

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.ui import Select
from selenium.webdriver.support.ui import WebDriverWait
from selenium.common.exceptions import TimeoutException
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import NoSuchElementException
from selenium.common.exceptions import NoAlertPresentException
import sys

import unittest, time, re

class Sel(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Firefox()
        self.driver.implicitly_wait(30)
        self.base_url = "https://twitter.com"
        self.verificationErrors = []
        self.accept_next_alert = True
    def test_sel(self):
        driver = self.driver
        delay = 3
        driver.get(self.base_url + "/search?q=stackoverflow&src=typd")
        driver.find_element_by_link_text("All").click()
        for i in range(1,100):
            self.driver.execute_script("window.scrollTo(0, document.body.scrollHeight);")
            time.sleep(4)
        html_source = driver.page_source
        data = html_source.encode('utf-8')


if __name__ == "__main__":
    unittest.main()

The for loop allows you to parse through the infinite scrolls and post which you can extract the loaded data.

Step 3 : Print the data if required.

回答3:

For infinite scrolling data are requested to Ajax calls. Open web browser --> network_tab --> clear previous requests history by clicking icon like stop--> scroll the webpage--> now you can find the new request for scroll event--> open the request header --> you can find the URL of request ---> copy and paste URL in an seperare tab--> you can find the result of Ajax call --> just form the requested URL to get the data page until end of the page