Python Web Crawling Tutorial: From Beginner to Hands-on

First, why you catch the web page is always blocked? First understand this pit

Folks just started using Python to grab data, nine out of ten have encountered the 403 error. Last month, a friend of a price comparison website was blocked by an e-commerce platform for three consecutive days with more than 20 IPs, and he was so anxious that he jumped straight to his feet. This thing is frankly like you go to the supermarket to try to eat, caught the same counter even eat more than a dozen times, the security guards can not drive you away?

That's when it's time toproxy IPto be your "stealth vest". For example, with ipipgo's rotating IP service, each request for a different "vest", the other server to see is a different visitor. Tested found that the reasonable use of proxy IP, the target site interception rate can be reduced to 5% below.

Second, hand to teach you with proxy IP (with a guide to avoid the pit)

Install both libraries first:
pip install requests
pip install fake_useragent

Here's the kicker! When using ipipgo's API to get a proxy IP, remember toException Retry Mechanism. Look at this code:

import requests
from fake_useragent import UserAgent

def get_proxy().
     Fill in the address of the API provided by ipipgo.
    resp = requests.get("https://ipipgo.com/api/getProxy")
    return {'http': f'http://{resp.text}', 'https': f'https://{resp.text}'}

ua = UserAgent()
headers = {'User-Agent': ua.random}

headers = {'User-Agent': ua.random}
    resp = requests.get('Target URL',
                      proxies=get_proxy(), headers=headers, ua.random} try: resp = requests.
                      headers=headers,
                      timeout=8)
except Exception as e.
    print(f "The {retry}th request failed, retrying...")

Note three key points:

Third, the real case: with ipipgo crawl dynamic data

Recently, I encountered an anti-climbing escalation while helping a client to capture data from a ticketing platform:

1. Ordinary proxy IP will be blocked after 5 consecutive requests.
2. Need to handle dynamic loading of pages
3. Captcha random trigger

Solution:
- Switch to ipipgo.Long-lasting premium IP(survives for 12 hours)
- Dynamic rendering with Selenium
- Setting the request frequency limiter

Final code structure:

from selenium.webdriver import ChromeOptions

options = ChromeOptions()
options.add_argument(f'--proxy-server={ipipgo_proxy}')
driver = webdriver.Chrome(options=options)

 Smart wait for loading
wait = WebDriverWait(driver, 10)
wait.until(EC.presence_of_element_located((By.CLASS_NAME, 'price')))

IV. Frequently Asked Questions QA (a must for newbies)

Q: What can I do about slow proxy IPs?
A: It is recommended to prioritize ipipgo'sBGP line，实测能控制在200ms以内。别贪便宜用免费代理，速度慢还不稳定。

Q: What should I do if I encounter a CAPTCHA?
A: You can call ipipgo's API to switch IP with the coding platform. The point is to actively change the IP before triggering the CAPTCHA.

Q: How can I tell if a proxy is in effect?
A: Add a test to the code:
print(requests.get('http://httpbin.org/ip', proxies=proxy).text)

V. Long-term maintenance techniques (the Great Law of the Save)

1. Check the quality of the IP pool weekly and clean up the invalid proxies in a timely manner
2. Set up intelligent switching strategy: according to the response time of the target website to automatically change the IP address.
3. The use of ipipgo's is recommended for important projects.Exclusive IP packageAvoiding Public IP Pollution
4. Regularly update the User-Agent library, do not let the site recognize you as a crawler

Finally, a true story: last year's double eleven an e-commerce platform blocked more than 200 IP, with ipipgo dynamic IP service customers all normal running. Engage in this matter of data capture, choose the right tool can really lose a lot of hair.