python - selenium with scrapy for dynamic page

91
votes

I'm trying to scrape product information from a webpage, using scrapy. My to-be-scraped webpage looks like this:

  • starts with a product_list page with 10 products
  • a click on "next" button loads the next 10 products (url doesn't change between the two pages)
  • i use LinkExtractor to follow each product link into the product page, and get all the information I need

I tried to replicate the next-button-ajax-call but can't get working, so I'm giving selenium a try. I can run selenium's webdriver in a separate script, but I don't know how to integrate with scrapy. Where shall I put the selenium part in my scrapy spider?

My spider is pretty standard, like the following:

class ProductSpider(CrawlSpider):
    name = "product_spider"
    allowed_domains = ['example.com']
    start_urls = ['http://example.com/shanghai']
    rules = [
        Rule(SgmlLinkExtractor(restrict_xpaths='//div[@id="productList"]//dl[@class="t2"]//dt'), callback='parse_product'),
        ]

    def parse_product(self, response):
        self.log("parsing product %s" %response.url, level=INFO)
        hxs = HtmlXPathSelector(response)
        # actual data follows

Any idea is appreciated. Thank you!

2
pythonseleniumselenium-webdriverweb-scrapingscrapy
stackoverflow.com/questions/50714354/… – Yash Pokar

2 Answers

131
votes

It really depends on how do you need to scrape the site and how and what data do you want to get.

Here's an example how you can follow pagination on ebay using Scrapy+Selenium:

import scrapy
from selenium import webdriver

class ProductSpider(scrapy.Spider):
    name = "product_spider"
    allowed_domains = ['ebay.com']
    start_urls = ['http://www.ebay.com/sch/i.html?_odkw=books&_osacat=0&_trksid=p2045573.m570.l1313.TR0.TRC0.Xpython&_nkw=python&_sacat=0&_from=R40']

    def __init__(self):
        self.driver = webdriver.Firefox()

    def parse(self, response):
        self.driver.get(response.url)

        while True:
            next = self.driver.find_element_by_xpath('//td[@class="pagn-next"]/a')

            try:
                next.click()

                # get the data and write it to scrapy items
            except:
                break

        self.driver.close()

Here are some examples of "selenium spiders":

There is also an alternative to having to use Selenium with Scrapy. In some cases, using ScrapyJS middleware is enough to handle the dynamic parts of a page. Sample real-world usage:

4
votes

If (url doesn't change between the two pages) then you should add dont_filter=True with your scrapy.Request() or scrapy will find this url as a duplicate after processing first page.

If you need to render pages with javascript you should use scrapy-splash, you can also check this scrapy middleware which can handle javascript pages using selenium or you can do that by launching any headless browser

But more effective and faster solution is inspect your browser and see what requests are made during submitting a form or triggering a certain event. Try to simulate the same requests as your browser sends. If you can replicate the request(s) correctly you will get the data you need.

Here is an example :

class ScrollScraper(Spider):
    name = "scrollingscraper"

    quote_url = "http://quotes.toscrape.com/api/quotes?page="
    start_urls = [quote_url + "1"]

    def parse(self, response):
        quote_item = QuoteItem()
        print response.body
        data = json.loads(response.body)
        for item in data.get('quotes', []):
            quote_item["author"] = item.get('author', {}).get('name')
            quote_item['quote'] = item.get('text')
            quote_item['tags'] = item.get('tags')
            yield quote_item

        if data['has_next']:
            next_page = data['page'] + 1
            yield Request(self.quote_url + str(next_page))

When pagination url is same for every pages & uses POST request then you can use scrapy.FormRequest() instead of scrapy.Request(), both are same but FormRequest adds a new argument (formdata=) to the constructor.

Here is another spider example form this post:

class SpiderClass(scrapy.Spider):
    # spider name and all
    name = 'ajax'
    page_incr = 1
    start_urls = ['http://www.pcguia.pt/category/reviews/#paginated=1']
    pagination_url = 'http://www.pcguia.pt/wp-content/themes/flavor/functions/ajax.php'

    def parse(self, response):

        sel = Selector(response)

        if self.page_incr > 1:
            json_data = json.loads(response.body)
            sel = Selector(text=json_data.get('content', ''))

        # your code here

        # pagination code starts here
        if sel.xpath('//div[@class="panel-wrapper"]'):
            self.page_incr += 1
            formdata = {
                'sorter': 'recent',
                'location': 'main loop',
                'loop': 'main loop',
                'action': 'sort',
                'view': 'grid',
                'columns': '3',
                'paginated': str(self.page_incr),
                'currentquery[category_name]': 'reviews'
            }
            yield FormRequest(url=self.pagination_url, formdata=formdata, callback=self.parse)
        else:
            return