I have a issue about scrapyd api.
I write simple spider, it gets domain url as a argument.
import scrapy
class QuotesSpider(scrapy.Spider):
name = 'quotes'
def __init__(self, domains=None):
self.allowed_domains = [domains]
self.start_urls = ['http://{}/'.format(domains)]
def parse(self, response):
# time.sleep(int(self.sleep))
item = {}
item['title'] = response.xpath('//head/title/text()').extract()
yield item
It works perfect if I run it like
scrapy crawl quotes -a domains=quotes.toscrape.com
But when time comes to run it via scrapyd_api it goes wrong:
from scrapyd_api import ScrapydAPI
scrapyd = ScrapydAPI('http://localhost:6800')
scrapyd.schedule(project='pd', spider='quotes', domains='http://quotes.toscrape.com/')
I get - builtins.TypeError: init() got an unexpected keyword argument '_job'
How can I start scrapy spiders via scrapyd api with args?
it is an answer.
According to this answer I was wrong with super method.
now my code looks like this:
class QuotesSpider(scrapy.Spider):
name = 'quotes'
start_urls = []
def __init__(self, *args, **kwargs):
super(QuotesSpider, self).__init__(*args, **kwargs)
self.allowed_domains = [kwargs.get('domains')]
self.start_urls.append('http://{}/'.format(kwargs.get('domains')))
Related
I did a lot of searches on the web but I couldn't find anything related or maybe it has to do with the wording used.
Basically, I would like to write a spider that would able to save the scraped links and to check if some other links have been already scraped. Is there any build in function in scrapy to do so?
Many thanks
You can write your own method for this purpose. I have written in my project and you can take reference from this. A dictionary called already_parsed_urls and for every callback, I am updating this dictionary.
You can look at the below code snippet and take reference.
from scrapy.spiders import CrawlSpider
from scrapy_splash import SplashRequest
class Spider(CrawlSpider):
name = 'test'
allowed_domains = []
web_url = ''
start_urls = ['']
counter = 0
already_parsed_urls = {}
wait_time = 3
timeout = '90'
def start_requests(self):
for start_url in self.start_urls:
yield SplashRequest(start_url, callback=self.parse_courses,
args={'wait': self.wait_time, 'timeout': self.timeout})
def parse_courses(self, response):
course_urls = []
yield SplashRequest(course_urls[0], callback=self.parse_items, args={'wait': self.wait_time})
def parse_items(self, response):
if not self.already_parsed_urls.get(response.url):
# Get Program URL
program_url = response.url
self.already_parsed_urls[response.url] = 1
else:
return {}
Looking to just count the number of things scraped. New to python and scraping just following the example and what to know how to just count the number of times Albert Einstein shows up and print to a json file. Just can not get it to print to file using print, yield, or return.
import scrapy
class QuotesSpider(scrapy.Spider):
name = "author"
start_urls = [
'http://quotes.toscrape.com/page/1/',
]
def parse(self, response):
i=0
for quote in response.css('div.quote'):
author = quote.css("small.author::text").get()
if author == "Albert Einstein":
i+=1
next_page = response.css('li.next a::attr(href)').get()
if next_page is not None:
yield response.follow(next_page, callback=self.parse)
I found out how to get to the item_scraped_count that shows up in the log output at the end of the spider.
import scrapy
from scrapy import signals
class CountSpider(scrapy.Spider):
name = 'count'
start_urls = ['https://example.com']
#classmethod
def from_crawler(cls, crawler, *args, **kwargs):
spider = super(CountSpider, cls).from_crawler(crawler, *args, **kwargs)
crawler.signals.connect(spider.spider_closed, signal=signals.spider_closed)
return spider
def spider_closed(self, spider):
stats = spider.crawler.stats.get_stats()
numcount = str(stats['item_scraped_count'])
Here I can create a csv file with the stats
In scrapy request are made asynchronously, and each request will callback to the parse function indepedently. Your i variable is not an instance variable, so it's scope is limited to each function call.
Even if that wasn't the case, the recursion would turn your counter to 0 in each callback.
I would suggest you to take a look at scrapy items, at the end of the scrapy process it will return a counter with the nr of scraped items. Although that maybe an overkill if you don't want to store anymore information but the number of occurrences of "Albert Einstein".
If that's all you want, you can use a dirtier solution, set your counter var to be a instance var and have parse method to increment it, like this:
import scrapy
class QuotesSpider(scrapy.Spider):
name = "author"
start_urls = [
'http://quotes.toscrape.com/page/1/',
]
counter = 0
def parse(self, response):
for quote in response.css('div.quote'):
author = quote.css("small.author::text").get()
if author == "Albert Einstein":
self.counter += 1
next_page = response.css('li.next a::attr(href)').get()
if next_page is not None:
yield response.follow(next_page, callback=self.parse)
I would like to repeatedly scrape the same URLs with different delays. After researching the issue it seemed that the appropriate solution was to use something like
nextreq = scrapy.Request(url, dont_filter=True)
d = defer.Deferred()
delay = 1
reactor.callLater(delay, d.callback, nextreq)
yield d
in parse.
However, I have been unable to make this work. I am getting the error message
ERROR: Spider must return Request, BaseItem, dict or None, got 'Deferred'
I am not familiar with twisted so I hope I am just missing something obvious
Is there a better way of achieving my goal that doesn't fight the framework so much?
I finally found an answer in an old PR
def parse():
req = scrapy.Request(...)
delay = 0
reactor.callLater(delay, self.crawler.engine.schedule, request=req, spider=self)
However, the spider can exit due to being idle too early. Based on the outdated middleware https://github.com/ArturGaspar/scrapy-delayed-requests, this can be remedied with
from scrapy import signals
from scrapy.exceptions import DontCloseSpider
class ImmortalSpiderMiddleware(object):
#classmethod
def from_crawler(cls, crawler):
s = cls()
crawler.signals.connect(s.spider_idle, signal=signals.spider_idle)
return s
#classmethod
def spider_idle(cls, spider):
raise DontCloseSpider()
The final option, updating the middleware by ArturGaspar, led to:
from weakref import WeakKeyDictionary
from scrapy import signals
from scrapy.exceptions import DontCloseSpider
from twisted.internet import reactor
class DelayedRequestsMiddleware(object):
requests = WeakKeyDictionary()
#classmethod
def from_crawler(cls, crawler):
ext = cls()
crawler.signals.connect(ext.spider_idle, signal=signals.spider_idle)
return ext
#classmethod
def spider_idle(cls, spider):
if cls.requests.get(spider):
spider.log("delayed requests pending, not closing spider")
raise DontCloseSpider()
def process_request(self, request, spider):
delay = request.meta.pop('delay_request', None)
if delay:
self.requests.setdefault(spider, 0)
self.requests[spider] += 1
reactor.callLater(delay, self.schedule_request, request.copy(),
spider)
raise IgnoreRequest()
def schedule_request(self, request, spider):
spider.crawler.engine.schedule(request, spider)
self.requests[spider] -= 1
And can be used in parse like:
yield Request(..., meta={'delay_request': 5})
Here is a simple python file--test.py.
import math
class myClass():
def myFun(self,x):
return(math.sqrt(x))
if __name__ == "__main__":
myInstance=myClass()
print(myInstance.myFun(9))
It print 3 with python test.py,let's analyse the running process.
1. to instance myClass and assign it to myInstance.
2.to call myFun function and print the result.
It is scrapy's turn.
In the scrapy1.4 manual,quotes_spider.py is as below.
import scrapy
class QuotesSpider(scrapy.Spider):
name = "quotes"
def start_requests(self):
urls = [
'http://quotes.toscrape.com/page/1/',
'http://quotes.toscrape.com/page/2/',
]
for url in urls:
yield scrapy.Request(url=url, callback=self.parse)
def parse(self, response):
page = response.url.split("/")[-2]
filename = 'quotes-%s.html' % page
with open(filename, 'wb') as f:
f.write(response.body)
self.log('Saved file %s' % filename)
To run the spider with scrapy crawl quotes,i am puzzled:
1.Where is the main function or main body for the spider?
2.Which class was instanced?
3.Which method was called?
mySpider = QuotesSpider(scrapy.Spider)
mySpider.parse(response)
How scrapy crawl work exactly?
So let's start. Assuming you use linux/mac. Let's check where us scrapy
$ which scrapy
/Users/tarun.lalwani/.virtualenvs/myproject/bin/scrapy
Let's look at the content of this file
$ cat /Users/tarun.lalwani/.virtualenvs/myproject/bin/scrapy
#!/Users/tarun.lalwani/.virtualenvs/myproject/bin/python3.6
# -*- coding: utf-8 -*-
import re
import sys
from scrapy.cmdline import execute
if __name__ == '__main__':
sys.argv[0] = re.sub(r'(-script\.pyw?|\.exe)?$', '', sys.argv[0])
sys.exit(execute())
So this executes execute method from cmdline.py and her is your main method.
cmdline.py
from __future__ import print_function
....
....
def execute(argv=None, settings=None):
if argv is None:
argv = sys.argv
# --- backwards compatibility for scrapy.conf.settings singleton ---
if settings is None and 'scrapy.conf' in sys.modules:
from scrapy import conf
if hasattr(conf, 'settings'):
settings = conf.settings
# ------------------------------------------------------------------
if settings is None:
settings = get_project_settings()
# set EDITOR from environment if available
try:
editor = os.environ['EDITOR']
except KeyError: pass
else:
settings['EDITOR'] = editor
check_deprecated_settings(settings)
# --- backwards compatibility for scrapy.conf.settings singleton ---
import warnings
from scrapy.exceptions import ScrapyDeprecationWarning
with warnings.catch_warnings():
warnings.simplefilter("ignore", ScrapyDeprecationWarning)
from scrapy import conf
conf.settings = settings
# ------------------------------------------------------------------
inproject = inside_project()
cmds = _get_commands_dict(settings, inproject)
cmdname = _pop_command_name(argv)
parser = optparse.OptionParser(formatter=optparse.TitledHelpFormatter(), \
conflict_handler='resolve')
if not cmdname:
_print_commands(settings, inproject)
sys.exit(0)
elif cmdname not in cmds:
_print_unknown_command(settings, cmdname, inproject)
sys.exit(2)
cmd = cmds[cmdname]
parser.usage = "scrapy %s %s" % (cmdname, cmd.syntax())
parser.description = cmd.long_desc()
settings.setdict(cmd.default_settings, priority='command')
cmd.settings = settings
cmd.add_options(parser)
opts, args = parser.parse_args(args=argv[1:])
_run_print_help(parser, cmd.process_options, args, opts)
cmd.crawler_process = CrawlerProcess(settings)
_run_print_help(parser, _run_command, cmd, args, opts)
sys.exit(cmd.exitcode)
if __name__ == '__main__':
execute()
Now if you notice execute method it processes the arguments passed by you. which is crawl quotes in your case. The execute methods scans the projects for classes and check which has name defined as quotes. It creates the CrawlerProcess class and that runs the whole show.
Scrapy is based on Twisted Python Framework. Which is a scheduler based framework.
Consider the below part of the code
for url in urls:
yield scrapy.Request(url=url, callback=self.parse)
When the engine executes this function and first yield is execute. The value is returned to the engined. The engine now looks at other task that are pending executes them, (when they yield, some other pending task queue function gets a chance). So yield is what allows to break a function execution into parts and help Scrapy/Twisted work.
You can get a detailed overview on the link below
https://doc.scrapy.org/en/latest/topics/architecture.html
How can I scrape multiple URLs with Scrapy?
Am I forced to make multiple crawlers?
class TravelSpider(BaseSpider):
name = "speedy"
allowed_domains = ["example.com"]
start_urls = ["http://example.com/category/top/page-%d/" % i for i in xrange(4),"http://example.com/superurl/top/page-%d/" % i for i in xrange(55)]
def parse(self, response):
hxs = HtmlXPathSelector(response)
items = []
item = TravelItem()
item['url'] = hxs.select('//a[#class="out"]/#href').extract()
out = "\n".join(str(e) for e in item['url']);
print out
Python says:
NameError: name 'i' is not defined
But when I use one URL it works fine!
start_urls = ["http://example.com/category/top/page-%d/" % i for i in xrange(4)"]
Your python syntax is incorrect, try:
start_urls = ["http://example.com/category/top/page-%d/" % i for i in xrange(4)] + \
["http://example.com/superurl/top/page-%d/" % i for i in xrange(55)]
If you need to write code to generate start requests, you can define a start_requests() method instead of using start_urls.
You can initialize start_urls in __init__.py method:
from scrapy.item import Item, Field
from scrapy.selector import HtmlXPathSelector
from scrapy.spider import BaseSpider
class TravelItem(Item):
url = Field()
class TravelSpider(BaseSpider):
def __init__(self, name=None, **kwargs):
self.start_urls = []
self.start_urls.extend(["http://example.com/category/top/page-%d/" % i for i in xrange(4)])
self.start_urls.extend(["http://example.com/superurl/top/page-%d/" % i for i in xrange(55)])
super(TravelSpider, self).__init__(name, **kwargs)
name = "speedy"
allowed_domains = ["example.com"]
def parse(self, response):
hxs = HtmlXPathSelector(response)
items = []
item = TravelItem()
item['url'] = hxs.select('//a[#class="out"]/#href').extract()
out = "\n".join(str(e) for e in item['url']);
print out
Hope that helps.
There are only four ranges in Python: LEGB, because the local scope of the class definition and the local extent of the list derivation are not nested functions, so they do not form the Enclosing scope.Therefore, they are two separate local scopes that cannot be accessed from each other.
so, don't use 'for' and class variables at the same time