I want to crawl an ASP.NET website but the urls are all the same how can I crawl specific pages using python?
here is the website I want to crawl:
http://www.fveconstruction.ch/index.htm
(I am using beautifulsoup, urllib and python 3)
What information should I get to distinguish a page from the other?
If the target website is just a single page application, it can't be crawled. As a workaround you can see the requests (GET, POST etc) that actually go when you manually navigate through the website and ask the crawler to use those. Or, teach your crawler to execute javascript at least what's on the target website.
It's the website who need to change to be easily crawlable, they need to provide a reasonable non-AJAX version of every page that needs to be indexed, or links to a page that needs to be indexed. Or use something like what pushState does in angularJs.
Related
I am scraping job posting data from a website using BeautifulSoup. I have working code that does what I need, but it only scrapes the first page of job postings. I am having trouble figuring out how to iteratively update the url to scrape each page. I am new to Python and have looked at a few different solutions to similar questions, but have not figured out how to apply them to my particular url. I think I need to iteratively update the url or somehow click the next button and then loop my existing code through each page. I appreciate any solutions.
url: https://jobs.utcaerospacesystems.com/search-jobs
First, BeautifulSoup doesn't have anything to do with GETing web pages - you get the webpage yourself, then feed it to bs4 for processing.
The problem with the page you linked is that it's javascript - it only renders correctly in a browser (or any other javascript VM).
#Fabricator is on the right track - you'll need to watch the developer console and see what the ajax requests the js is sending to the server. In this case, also take a look at the query string params, which include a param called CurrentPage - that's probably the one you want to focus on.
Can we use Scrapy for getting content from a web page which is loaded by Javascript?
I'm trying to scrape usage examples from this page,
but since they are loaded using Javascript as a JSON object I'm not able to get them with Scrapy.
Could you suggest what is the best way to deal with such issues?
Open your browser's developer tools and look at the Network tab. If you hit the "next" button on that page enough, it'll send out a new request:
After removing the JSONP paramter, the URL is pretty straightforward:
https://corpus.vocabulary.com/api/1.0/examples.json?query=unalienable&maxResults=24&startOffset=24&filter=0
By making the minimal number of requests, your spider will be fast.
If you want to just emulate a full browser and execute the JavaScript, you can use something like Selenium or Scrapinghub's Splash (and its corresponding Scrapy plugin).
The homepage of the website I'm trying to scrape displays four tabs, one of which reads "[Number] Available Jobs". I'm interested in scraping the [Number] value. When I inspect the page in Chrome, I can see the value enclosed within a <span> tag.
However, there is nothing enclosed in that <span> tag when I view the page source directly. I was planning on using the Python requests module to make an HTTP GET request and then use regex to capture the value from the returned content. This is obviously not possible if the content doesn't contain the number I need.
My questions are:
What is happening here? How can a value be dynamically loaded into a
page, displayed, and then not appear within the HTML source?
If the value doesn't appear in the page source, what can I do to
reach it?
If the content doesn't appear in the page source then it is probably generated using javascript. For example the site might have a REST API that lists jobs, and the Javascript code could request the jobs from the API and use it to create the node in the DOM and attach it to the available jobs. That's just one possibility.
One way to scrap this information is to figure out how that javascript works and make your python scraper do the same thing (for example, if there is a simple REST API it is using, you just need to make a request to that same URL). Often that is not so easy, so another alternative is to do your scraping using a javascript capable browser like selenium.
One final thing I want to mention is that regular expressions are a fragile way to parse HTML, you should generally prefer to use a library like BeautifulSoup.
1.A value can be loaded dynamically with ajax, ajax loads asynchronously that means that the rest of the site does not wait for ajax to be rendered, that's why when you get the DOM the elements loaded with ajax does not appear in it.
2.For scraping dynamic content you should use selenium, here a tutorial
for data that load dynamically you should look for an xhr request in the networks and if you can make that data productive for you than voila!!
you can you phantom js, it's a headless browser and it captures the html of that page with the dynamically loaded content.
I'd like to know if is it possible to browse all links in a site (including the parent links and sublinks) using python selenium (example: yahoo.com),
fetch all links in the homepage,
open each one of them
open all the links in the sublinks to three four levels.
I'm using selenium on python.
Thanks
Ala'a
You want "web-scraping" software like Scrapy and possibly Beautifulsoup4 - the first is used to build a program called a "spider" which "crawls" through web pages, extracting structured data from them, and following certain (or all) links in them. BS4 is also for extracting data from web pages, and combined with libraries like requests can be used to build your own spider, though at this point something like Scrapy is probably more relevant to what you need.
There are numerous tutorials and examples out there to help you - just start with the google search I linked above.
Sure it is possible, but you have to instruct selenium to enter these links one by one as you are working within one browser.
In case, the pages are not having the links rendered by JavaScript in the browser, it would be much more efficient to fetch these pages by direct http request and process it this way. In this case I would recommend using requests. However, even with requests it is up to your code to locate all urls in the page and follow up with fetching those pages.
There might be also other Python packages, which are specialized on this kind of task, but here I cannot serve with real experience.
I'm trying to scrape some information from a web site, but am having trouble reading the relevant pages. The pages seem to first send a basic setup, then more detailed info. My download attempts only seem to capture the basic setup. I've tried urllib and mechanize so far.
Firefox and Chrome have no trouble displaying the pages, although I can't see the parts I want when I view page source.
A sample url is https://personal.vanguard.com/us/funds/snapshot?FundId=0542&FundIntExt=INT
I'd like, for example, average maturity and average duration from the lower right of the page. The problem isn't extracting that info from the page, it's downloading the page so that I can extract the info.
The page uses JavaScript to load the data. Firefox and Chrome are only working because you have JavaScript enabled - try disabling it and you'll get a mostly empty page.
Python isn't going to be able to do this by itself - your best compromise would be to control a real browser (Internet Explorer is easiest, if you're on Windows) from Python using something like Pamie.
The website loads the data via ajax. Firebug shows the ajax calls. For the given page, the data is loaded from https://personal.vanguard.com/us/JSP/Funds/VGITab/VGIFundOverviewTabContent.jsf?FundIntExt=INT&FundId=0542
See the corresponding javascript code on the original page:
<script>populator = new Populator({parentId:
"profileForm:vanguardFundTabBox:tab0",execOnLoad:true,
populatorUrl:"/us/JSP/Funds/VGITab/VGIFundOverviewTabContent.jsf?FundIntExt=INT&FundId=0542",
inline:fals e,type:"once"});
</script>
The reason why is because it's performing AJAX calls after it loads. You will need to account for searching out those URLs to scrape it's content as well.
As RichieHindle mentioned, your best bet on Windows is to use the WebBrowser class to create an instance of an IE rendering engine and then use that to browse the site.
The class gives you full access to the DOM tree, so you can do whatever you want with it.
http://msdn.microsoft.com/en-us/library/system.windows.forms.webbrowser(loband).aspx