如何在scrapy中设置优先级
How to set priorities in scrapy
尝试抓取网页，我需要设置优先级以便按顺序抓取它们。现在它想抓取每个 url 的所有第 1 页，然后是所有第 2 页，依此类推。但是我需要它来抓取 url 1 的所有页面和 url 2 的所有页面等等。我一直在尝试通过将第一个 url 设置为最高优先级来使用优先级来做到这一点，这将是 csv 文件中 url 的数量。但它不起作用，主要是因为我不能减少优先级值，因为它在一个 for 循环中所以每次进入循环它都会将优先级重置为原始数字，所以每次都相同所以它们都具有相同的优先级.我怎样才能让优先级正常工作，以便按照我想要的顺序抓取 urls。
SplashSpider.py
class MySpider(Spider):
# Name of Spider
name = 'splash_spider'
# getting all the url + ip address + useragent pairs then request them
def start_requests(self):
# get the file path of the csv file that contains the pairs from the settings.py
with open(self.settings["PROXY_CSV_FILE"], mode="r") as csv_file:
# requests is a list of dictionaries like this -> {url: str, ua: str, ip: str}
requests = process_csv(csv_file)
for i, req in enumerate(requests):
x = len(requests) - i # <- check here
# Return needed url with set delay of 3 seconds
yield SplashRequest(url=req["url"], callback=self.parse, args={"wait": 3},
# Pair with user agent specified in csv file
headers={"User-Agent": req["ua"]},
# Sets splash_url to whatever the current proxy that goes with current URL is instead of actual splash url
splash_url = req["ip"],
priority = x,
meta={'priority': x}
)
更新 #1
# Scraping function that will scrape URLs for specified information
def parse(self, response):
# Initialize item to function GameItem located in items.py, will be called multiple times
item = GameItem()
# Initialize saved_name
saved_name = ""
# Extract card category from URL using html code from website that identifies the category. Will be outputted before rest of data
item["Category"] = response.css("span.titletext::text").get()
# For loop to loop through HTML code until all necessary data has been scraped
for game in response.css("tr[class^=deckdbbody]"):
# Initialize saved_name to the extracted card name
saved_name = game.css("a.card_popup::text").get() or saved_name
# Now call item and set equal to saved_name and strip leading '\n' from output
item["Card_Name"] = saved_name.strip()
# Check to see if output is null, in the case that there are two different conditions for one card
if item["Card_Name"] != None:
# If not null than store value in saved_name
saved_name = item["Card_Name"].strip()
# If null then set null value to previous card name since if there is a null value you should have the same card name twice
else:
item["Card_Name"] = saved_name
# Call item again in order to extract the condition, stock, and price using the corresponding html code from the website
item["Condition"] = game.css("td[class^=deckdbbody].search_results_7 a::text").get()
item["Stock"] = game.css("td[class^=deckdbbody].search_results_8::text").get()
item["Price"] = game.css("td[class^=deckdbbody].search_results_9::text").get()
if item["Price"] == None:
item["Price"] = game.css("td[class^=deckdbbody].search_results_9 span[style*='color:red']::text").get()
# Return values
yield item
priority = response.meta['priority']
# Finds next page button
next_page = response.xpath('//a[contains(., "- Next>>")]/@href').get()
# If it exists and there is a next page enter if statement
if next_page is not None:
# Go to next page
yield response.follow(next_page, self.parse, priority=priority, meta={'priority': priority})
更新 2
2019-06-13 15:16:23 [scrapy.core.scraper] ERROR: Spider error processing <GET http://www.starcitygames.com/catalog/category/1014?&start=50> (referer: http://www.starcitygames.com/catalog/category/Visions)
Traceback (most recent call last):
File "/usr/local/lib/python3.6/site-packages/scrapy/utils/defer.py", line 102, in iter_errback
yield next(it)
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/offsite.py", line 29, in process_spider_output
for x in result:
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/referer.py", line 339, in <genexpr>
return (_set_referer(r) for r in result or ())
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/urllength.py", line 37, in <genexpr>
return (r for r in result or () if _filter(r))
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/depth.py", line 58, in <genexpr>
return (r for r in result or () if _filter(r))
File "/usr/home/north/scrapy_splash/scrapy_javascript/scrapy_javascript/spiders/SplashSpider.py", line 104, in parse
priority = response.meta['priority']
KeyError: 'priority'
要通过数组改变它们，最好这样做：
for i, req in enumerate(requests):
x = len(requests) - i # <- check here
# Return needed url with set delay of 3 seconds
yield SplashRequest(url=req["url"], callback=self.parse, args={"wait": 3},
# Pair with user agent specified in csv file
headers={"User-Agent": req["ua"]},
# Sets splash_url to whatever the current proxy that goes with current URL is instead of actual splash url
splash_url = req["ip"],
priority = x,
meta={'priority': x} # <- check here!!
)
并且不要忘记使用，例如，meta 来传递当前优先级（我不记得是否可以从响应中获取它）以将其传递给每个子请求。
更新：
def parse(self, response):
# I skip you logic here
priority = response.meta['priority']
next_page = response.xpath('//a[contains(., "- Next>>")]/@href').get()
# If it exists and there is a next page enter if statement
if next_page is not None:
# Go to next page
yield response.follow(next_page, self.parse, priority=priority, meta={'priority': priority})
尝试抓取网页，我需要设置优先级以便按顺序抓取它们。现在它想抓取每个 url 的所有第 1 页，然后是所有第 2 页，依此类推。但是我需要它来抓取 url 1 的所有页面和 url 2 的所有页面等等。我一直在尝试通过将第一个 url 设置为最高优先级来使用优先级来做到这一点，这将是 csv 文件中 url 的数量。但它不起作用，主要是因为我不能减少优先级值，因为它在一个 for 循环中所以每次进入循环它都会将优先级重置为原始数字，所以每次都相同所以它们都具有相同的优先级.我怎样才能让优先级正常工作，以便按照我想要的顺序抓取 urls。
SplashSpider.py
class MySpider(Spider):
# Name of Spider
name = 'splash_spider'
# getting all the url + ip address + useragent pairs then request them
def start_requests(self):
# get the file path of the csv file that contains the pairs from the settings.py
with open(self.settings["PROXY_CSV_FILE"], mode="r") as csv_file:
# requests is a list of dictionaries like this -> {url: str, ua: str, ip: str}
requests = process_csv(csv_file)
for i, req in enumerate(requests):
x = len(requests) - i # <- check here
# Return needed url with set delay of 3 seconds
yield SplashRequest(url=req["url"], callback=self.parse, args={"wait": 3},
# Pair with user agent specified in csv file
headers={"User-Agent": req["ua"]},
# Sets splash_url to whatever the current proxy that goes with current URL is instead of actual splash url
splash_url = req["ip"],
priority = x,
meta={'priority': x}
)
更新 #1
# Scraping function that will scrape URLs for specified information
def parse(self, response):
# Initialize item to function GameItem located in items.py, will be called multiple times
item = GameItem()
# Initialize saved_name
saved_name = ""
# Extract card category from URL using html code from website that identifies the category. Will be outputted before rest of data
item["Category"] = response.css("span.titletext::text").get()
# For loop to loop through HTML code until all necessary data has been scraped
for game in response.css("tr[class^=deckdbbody]"):
# Initialize saved_name to the extracted card name
saved_name = game.css("a.card_popup::text").get() or saved_name
# Now call item and set equal to saved_name and strip leading '\n' from output
item["Card_Name"] = saved_name.strip()
# Check to see if output is null, in the case that there are two different conditions for one card
if item["Card_Name"] != None:
# If not null than store value in saved_name
saved_name = item["Card_Name"].strip()
# If null then set null value to previous card name since if there is a null value you should have the same card name twice
else:
item["Card_Name"] = saved_name
# Call item again in order to extract the condition, stock, and price using the corresponding html code from the website
item["Condition"] = game.css("td[class^=deckdbbody].search_results_7 a::text").get()
item["Stock"] = game.css("td[class^=deckdbbody].search_results_8::text").get()
item["Price"] = game.css("td[class^=deckdbbody].search_results_9::text").get()
if item["Price"] == None:
item["Price"] = game.css("td[class^=deckdbbody].search_results_9 span[style*='color:red']::text").get()
# Return values
yield item
priority = response.meta['priority']
# Finds next page button
next_page = response.xpath('//a[contains(., "- Next>>")]/@href').get()
# If it exists and there is a next page enter if statement
if next_page is not None:
# Go to next page
yield response.follow(next_page, self.parse, priority=priority, meta={'priority': priority})
更新 2
2019-06-13 15:16:23 [scrapy.core.scraper] ERROR: Spider error processing <GET http://www.starcitygames.com/catalog/category/1014?&start=50> (referer: http://www.starcitygames.com/catalog/category/Visions)
Traceback (most recent call last):
File "/usr/local/lib/python3.6/site-packages/scrapy/utils/defer.py", line 102, in iter_errback
yield next(it)
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/offsite.py", line 29, in process_spider_output
for x in result:
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/referer.py", line 339, in <genexpr>
return (_set_referer(r) for r in result or ())
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/urllength.py", line 37, in <genexpr>
return (r for r in result or () if _filter(r))
File "/usr/local/lib/python3.6/site-packages/scrapy/spidermiddlewares/depth.py", line 58, in <genexpr>
return (r for r in result or () if _filter(r))
File "/usr/home/north/scrapy_splash/scrapy_javascript/scrapy_javascript/spiders/SplashSpider.py", line 104, in parse
priority = response.meta['priority']
KeyError: 'priority'
要通过数组改变它们，最好这样做：
for i, req in enumerate(requests):
x = len(requests) - i # <- check here
# Return needed url with set delay of 3 seconds
yield SplashRequest(url=req["url"], callback=self.parse, args={"wait": 3},
# Pair with user agent specified in csv file
headers={"User-Agent": req["ua"]},
# Sets splash_url to whatever the current proxy that goes with current URL is instead of actual splash url
splash_url = req["ip"],
priority = x,
meta={'priority': x} # <- check here!!
)
并且不要忘记使用，例如，meta 来传递当前优先级（我不记得是否可以从响应中获取它）以将其传递给每个子请求。
更新：
def parse(self, response):
# I skip you logic here
priority = response.meta['priority']
next_page = response.xpath('//a[contains(., "- Next>>")]/@href').get()
# If it exists and there is a next page enter if statement
if next_page is not None:
# Go to next page
yield response.follow(next_page, self.parse, priority=priority, meta={'priority': priority})