python - 使用 python web 抓取获取 UnboundLocalError
问题描述
我为亚马逊网络抓取编写了一个代码,我的代码适用于所有亚马逊产品,但它确实适用于我不知道的某些特定产品,它为某些产品显示的错误是 UnboundLocalError: local variable 'reviews' referenced在分配之前,请您指导我如何解决这个问题,谢谢!这是代码:
import requests
from bs4 import BeautifulSoup as bs
import json
import random
import os.path
import time
import pandas as pd
def scrape_products(response):
dataframe = pd.DataFrame()
res = pd.DataFrame()
# Checking if response is okay or not
if response.ok:
response = response.text
content = bs(response,'lxml')
# Selecting products
items = content.find_all('li' , class_ = 'zg-item-immersion')
for item in items:
# Selecting data about each product
count = item.find('span' , class_ = 'zg-badge-text').text.strip()
title = item.find('div' , class_ = 'p13n-sc-truncate').text.strip()
price = item.find('span' , class_ = 'p13n-sc-price')
try:
rating = item.find('span' , class_ = 'a-icon-alt').text.strip()
total = item.find('a' , class_ = 'a-size-small a-link-normal').text.strip()
reviews = item.find('div' , class_ = 'a-icon-row a-spacing-none').find('a',class_='a-link-normal').get('href')
except:
pass
image_url = item.find('div' , class_ = 'a-section a-spacing-small').find('img').get('src')
go_to = item.find('span', class_ = 'a-list-item').find('a' , class_ = 'a-link-normal').get('href')
product_url = 'https://www.amazon.com' + go_to
# product_url = product_url.replace('?','/ref=zg_bs_2399939011_1?')
reviews_url = 'https://www.amazon.com' + reviews
# desc = requests.get(product_url)
# print(desc.status_code)
# if desc.ok:
# desc = desc.text
# data = bs(desc,'lxml')
# old_price = data.find('span',class_='priceBlockStrikePriceString a-text-strike').text
# if(old_price):
# print(old_price)
# else:
# pass
print('************************************************ ' + count +' **********************************************')
print('Title: {}'.format(title + '\n'))
if(price):
price = price.text.strip()
price = price[1:]
print('Price: {}'.format(price))
else:
pass
print('Rating: {} ({})'.format(rating , total))
print('Reviews Url: {}'.format(reviews_url))
print('Image Url: {}'.format(image_url))
print('Product Url: {}'.format(product_url))
print()
print()
data = {'Title':[title], 'Price':[price], 'Rating':[str(rating) +'('+ str(total)+')'],
'Reviews Url':[reviews_url], 'Image Url': [image_url], 'Product Url':[product_url]}
df = pd.DataFrame(data)
dataframe = dataframe.append(df)
return dataframe
def main():
page_1 = 'https://www.amazon.com/Best-Sellers-Amazon-Device-Smart-Locks/zgbs/amazon-devices/17295887011/ref=zg_bs_nav_3_5499877011'
#page_2 = 'https://www.amazon.com/Best-Sellers-Fire-Tablets-Bundles/zgbs/amazon-devices/17142718011/ref=zg_bs_pg_1?_encoding=UTF8&pg=2'
response_1 = requests.get(page_1)
#response_2 = requests.get(page_2)
df1 = scrape_products(response_1)
#df2 = scrape_products(response_2)
#df = df1.append(df2)
df1.Price = df1.Price.astype(float)
df1 = df1.sort_values(by=['Price'])
df1.to_csv('AMAZON\Amazon Devices & Accessories\Amazon Device Accessories\Best Sellers in Amazon Device Smart Locks.csv',index=False)
if __name__== "__main__":
main()
解决方案
您设置reviews
了一个 try/except 块,它只是忽略错误......并且没有设置reviews
. 在这种情况下,分配前的reviews_url = 'https://www.amazon.com' + reviews
引用。reviews
更糟糕的是,rating
,total
并且reviews
可能是前一个循环中的陈旧数据,默默地抽出坏数据。您需要一个处理错误的策略,例如跳过该项目
try:
rating = item.find('span' , class_ = 'a-icon-alt').text.strip()
total = item.find('a' , class_ = 'a-size-small a-link-normal').text.strip()
reviews = item.find('div' , class_ = 'a-icon-row a-spacing-none').find('a',class_='a-link-normal').get('href')
except:
print("ERROR scanning {}, ignored".format(item))
import traceback
traceback.print_exc()
continue
捕捉赤裸裸的异常是个坏主意。它掩盖了错误以及预期的错误。当您打印出错误时,您会感觉到可以忽略哪些内容并将异常处理程序更新为
except (IndexError, ValueError) as e:
....
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