How to solve the problem of missing dynamic loading content when obtaining web page data?

Python crawler: Challenges of requests library and dynamic web content

When using Python's requests library to crawl web page data, you often encounter situations where the content you get is inconsistent with the browser's display results, especially when dealing with dynamically loaded web pages. This article will analyze such problems and provide solutions based on selenium library.

Problem: Conflict between static crawling and dynamic content

Many websites use JavaScript to load content dynamically. requests library can only obtain the initial HTML source code of the web page and cannot execute JavaScript code, resulting in the missing content dynamically loaded.

For example, try to use requests to obtain a certain logistics information web page (the address is omitted to protect privacy):

 import requests

url = '...' # Logistics Information Web Address Headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36 Edg/114.0.1823.58'
}
response = requests.get(url, headers=headers)
html_content = response.content.decode('utf-8')

Since the web page uses JavaScript to load logistics information dynamically, html_content obtained by requests will lack key data.

Solution: Selenium simulates browser behavior

To solve this problem, we can use the selenium library to simulate browser behavior, execute JavaScript code and get the complete web page content.

 import time
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

# Set the browser driver path (please modify it according to the actual situation)
driver_path = '/path/to/chromedriver'  
driver = webdriver.Chrome(executable_path=driver_path)

url = '...' # Logistics information web address driver.get(url)

# Use explicit wait to ensure that the page loads complete (avoid element positioning failure)
try:
    element = WebDriverWait(driver, 10).until(
        EC.presence_of_element_located((By.ID, 'logisticsInfo')) # Modify according to the actual web page element ID)
    logistics_info = element.text
    print(logistics_info)
except:
    print("Logistics information element not found")

driver.quit()

This code uses selenium to open the web page, and uses WebDriverWait to wait for the specific element to appear, ensuring that the page is fully loaded before extracting the logistics information (assuming that the logistics information is located in an element with id 'logisticsInfo', please modify it according to the actual situation). Remember to install the necessary drivers and replace /path/to/chromedriver for your actual path to chromedriver.

Through selenium , we can overcome the limitations of requests when processing dynamic web pages and effectively obtain dynamically loaded web page content. Note that By.ID and 'logisticsInfo' need to be adjusted according to the actual HTML structure of the landing page.

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