为什么我的HTML解析器未输出想要的数字

Question

import requests
from bs4 import BeautifulSoup
import time

# URL of the website to monitor
url = 'https://nbeub.ca/index.php?page=current-petroleum-prices-2'

# Function to fetch the number from the website
def fetch_number():
    response = requests.get(url)
    soup = BeautifulSoup(response.text, 'html.parser')
    
    # Adjust the selector to find the specific number
    number = soup.select_one('body > table > tbody > tr:nth-child(5) > td > table > tbody > tr > td > table > tbody > tr > td:nth-child(3) > table > tbody > tr:nth-child(3) > td:nth-child(2)')
    return str(number)

# Main monitoring function
def monitor():
    last_number = fetch_number()
    print(f"Initial number: {last_number}")

    while True:
        time.sleep(2592000)  # Wait for 30 days before checking again
        current_number = fetch_number()
        
        if current_number != last_number:
            print(f"Number updated: {current_number}")
            last_number = current_number

# Start monitoring
monitor()

我的终端是正常的要求我提供输入

大多数桌子都没有

<tbody>

元素，

Answer 1

直接嵌套在

<table>

中。而不是使用所有这些直接子选择器，而是使用没有

> tbody >

的后代选择器，因此它都可以匹配两种方式。

number = soup.select_one('body > table tr:nth-child(5) > td > table tr > td > table tr > td:nth-child(3) > table tr:nth-child(3) > td:nth-child(2)')