How to scrape dynamic content from a website?

问题

So I'm using scrapy to scrape a data from Amazon books section. But somehow I got to know that it has some dynamic data. I want to know how dynamic data can be extracted from the website. Here's something I've tried so far:

import scrapy
from ..items import AmazonsItem

class AmazonSpiderSpider(scrapy.Spider):
    name = 'amazon_spider'
    start_urls = ['https://www.amazon.in/s?k=agatha+christie+books&crid=3MWRDVZPSKVG0&sprefix=agatha%2Caps%2C269&ref=nb_sb_ss_i_1_6']

    def parse(self, response):
        items =  AmazonsItem()
        products_name = response.css('.s-access-title::attr("data-attribute")').extract()
        for product_name in products_name:
            print(product_name)
        next_page = response.css('li.a-last a::attr(href)').get()
            if next_page is not None:
                next_page = response.urljoin(next_page)
                yield scrapy.Request(next_page, callback=self.parse)

Now I was using SelectorGadget to select a class which I have to scrape but in case of a dynamic website, it doesn't work.

So how do I scrape a website which has dynamic content?
what exactly is the difference between dynamic and static content?
How do I extract other information like price and image from the website? and how to get particular classes for example like a price?
how would I know that data is dynamically created?

回答1:

So how do I scrape a website which has dynamic content?

there are a few options:

Use Selenium, which allows you to simulate opening a browser, letting the page render, then pull the html source code
Sometimes you can look at the XHR and see if you can fetch the data directly (like from an API)
Sometimes the data is within the <script> tags of the html source. You could search through those and use json.loads() once you manipulate the text into a json format

what exactly is the difference between dynamic and static content?

Dynamic means the data is generated from a request after the initial page request. Static means all the data is there at the original call to the site

How do I extract other information like price and image from the website? and how to get particular classes for example like a price?

Refer to your first question

how would I know that data is dynamically created?

You'll know it's dynamically created if you see it in the dev tools page source, but not in the html page source you first request. You can also see if the data is generated by additional requests in the dev tool and looking at Network -> XHR

Lastly

Amazon does offer an API to access the data. Try looking into that as well

回答2:

If you want to load dynamic content, you will need to simulate a web browser. When you make an HTTP request, you will only get the text returned by that request, and nothing more. To simulate a web browser, and interact with data on the browser, use the selenium package for Python:

https://selenium-python.readthedocs.io/

回答3:

For scraping dynamic content (like JScript) you can use Srapy Splash. Look at this: https://www.google.com/amp/s/blog.scrapinghub.com/2015/03/02/handling-javascript-in-scrapy-with-splash%3fhs_amp=true

回答4:

So how do I scrape a website which has dynamic content?

Websites that have dynamic content have their own APIs from where they are pulling data. That data is not even fixed it will be different if you will check it after some time. But, it does not mean that you can't scrape a dynamic website. You can use automated testing frameworks like Selenium or Puppeteer.

what exactly is the difference between dynamic and static content?

As I have explained this in your first question, the static data is fixed and will remain the same forever but the dynamic data will be periodically updated or changes asynchronously.

How do I extract other information like price and image from the website? and how to get particular classes for example like a price?

for that, you can use libraries like BeautifulSoup in python and cheerio in Nodejs. Their docs are quite easy to understand and I will highly recommend you to read them thoroughly. You can also follow this tutorial

how would I know that data is dynamically created?

While reloading the page open the network tab in chrome dev tools. You will see a lot of APIs are working behind to provide the relevant data according to the page you are trying to access. In that case, the website is dynamic.

来源：https://stackoverflow.com/questions/55709463/how-to-scrape-dynamic-content-from-a-website

标签

python

dynamic

scrapy