Develop Reference

What information do I need when scraping a website that requires logging in?

I want to access my business' database on some site and scrape it using Python (I'm using Requests and BS4, I can go further if needed). But I couldn't.
Can someone provide us with info and simple resources on how to scrape such sites.
I'm not talking about providing usernames and passwords. The site requires much more than this.
How do I know the info I am required to provide for my script aside of UN and PW(e.g. how do I know that I must provide, say, an auth token)?
How to deal with the site when there are no HTTP URLs, but hrefs in the form of javascript:__doPostBack?
And in this regard, how do I transit from the logging in page to the page I want (the one contained in the aforementioned mentioned javascript:__doPostBack)?
Are the libraries I'm using enough? or do you recommend using—and learning in my case—something else?
Your help is greatly appreciated and thanked.

You didn't mention what you use for scraping, but since this sounds like a lot of the interaction on this site is based on client-side code, I'd suggest using a real browser to do the scraping, and interacting with the site not using low-level HTTP requests but using client side interaction (such as typing in elements or clicking buttons). This way, you don't need to worry about what form data to send or how to get the URLs of links yourself.
One recommended method of doing this would be to use BeutifulSoup with Selenium / WebDriver. There are multiple resources on how to do this, for example: How can I parse a website using Selenium and Beautifulsoup in python?

Python - how to trick anti adblock filter while scraping?

I`m trying to download content of a website using python urllib, but i have a problem because the site has an addblock filter and only thing i can get is text that asks me to disable addblock... Is there any way to trick this kind of filter?
Thanks in advance. (:

Javascript Parsing
The issue you are running into is a JavaScript filter that loads data after the page has loaded. The message that warns that you are using adblock is there in raw HTML and is completely static. It is replaced when a JavaScript call is able to validate where adblock is or is not present. There are several ways you can get around this, however each requires finding some way of loading JavaScript.
Solution(s)
There are several solutions to your problem. You can read more about them here.
Embed a web browser within an application and simulate a normal user.
Remotely connect to a web browser and automate it from a scripting
language.
Use special purpose add-ons to automate the browser
Use a framework/library to simulate a complete browser.
As you can see each one in some way requires emulating a browser and DOM objects. Since there are several libraries to help you accomplish this, I highly recommend you look into the url above.
The following is a code example from the same page that shows how to retrieve the URLs on a page that generates URLs via JavaScript. It relies on a library from gargoylesoftware.
import com.gargoylesoftware.htmlunit.WebClient as WebClient
import com.gargoylesoftware.htmlunit.BrowserVersion as BrowserVersion
def main():
webclient = WebClient(BrowserVersion.FIREFOX_3_6) # creating a new webclient object.
url = "http://www.gartner.com/it/products/mq/mq_ms.jsp"
page = webclient.getPage(url) # getting the url
articles = page.getByXPath("//table[#id='mqtable']//tr/td/a") # getting all the hyperlinks
if __name__ == '__main__':
main()
However,
I am not sure why you are scraping a webpage, or what website you are scraping it from. However, it is against the terms and conditions of various sites to automate such data-collection, and I advise your revise these terms before you get yourself into any trouble.
Further Research
If you are looking for a more generic answer to your question (e.g. "How can I load javascript with Python.") I highly recommend looking at previous answers on this site, because they offer some really good insight into the matter:
Web-scraping JavaScript page with Python

python open web page and get source code

We have developed a web based application, with user login etc, and we developed a python application that have to get some data on this page.
Is there any way to communicate python and system default browser ?
Our main goal is to open a webpage, with system browser, and get the HTML source code from it ? We tried with python webbrowser, opened web page succesfully, but could not get source code, and tried with urllib2, in that case, i think we have to use system default browser's cookie etc, and i dont want to this, because of security.

https://pypi.python.org/pypi/selenium
You can try to use Selenium, he was done for testing, but nothing prevents you from using it for other purposes

If your web site is navigable without Javascript, then you could try Mechanize or zope.testbrowser. These tools offer a higher level API than urllib2, letting you do things like follow links on pages and fill out HTML forms.
This can be helpful in navigating a site that uses cookie based authentication with HTML forms for login, for example.

Have a look at the nltk module---they have some utilities for looking at web pages and getting text. There's also BeautifulSoup, which is a bit more elaborate. I'm currently using both to scrape web pages for a learning algorithm---they're pretty widely used modules, so that means you can find lots of hints here :)

Python 3 - way to interact with a web page

I have experience with reading and extracting html source 'as given'(via urllib.request), but now I would like to perform browser-alike actions(like filling a form, or selecting a value from the option menu) and then, of course, read a resulting html code as usual. I did come across some modules that seemed promising, but turned out not supporting Python 3.
So, I'm here asking for a name of library/module that does the wanted, or pointing to a solution within standard libraries if it's there and I failed to see it.

Usually many websites (like Twitter, facebook or Wikipedia) provide their API's to let developers hook into their app and perform activities programmatically. For what so ever web site you wish to perform activities through code, just look for their API support.
In case you need to do web scraping, you can use scrapy. But it only has support upto python 2.7.x. Anyways, you can use requests for HTTP client and beautiful soup for HTML parsing.

Retrieve cookie created using javascript in python

I've had a look at many tutorials regarding cookiejar, but my problem is that the webpage that i want to scape creates the cookie using javascript and I can't seem to retrieve the cookie. Does anybody have a solution to this problem?

If all pages have the same JavaScript then maybe you could parse the HTML to find that piece of code, and from that get the value the cookie would be set to?
That would make your scraping quite vulnerable to changes in the third party website, but that's most often the case while scraping. (Please bear in mind that the third-party website owner may not like that you're getting the content this way.)

I responded to your other question as well: take a look at mechanize. It's probably the most fully featured scraping module I know: if the cookie is sent, then I'm sure you can get to it with this module.

Maybe you can execute the JavaScript code in a JavaScript engine with Python bindings (like python-spidermonkey or pyv8) and then retrieve the cookie. Or, as the javascript code is executed client side anyway, you may be able to convert the cookie-generating code to Python.

You could access the page using a real browser, via PAMIE, win32com or similar, then the JavaScript will be running in its native environment.