- Python Web Scraping Tutorial
Here's how to scrape a website for content and more with the Beautiful Soup Python library. Beautiful Soup is an open-source Python library. It uses navigating parsers to scrape the content of XML and HTML files. You need data for several analytical purposes. Here are some sites that you can use for training while learning how to use the Web Scraper. E-commerce site E-commerce site with multiple categories, subcategories. A better way to go about collecting data is to crawl data off the web, in short, web scraping. Once you have set up a system to crawl data from certain sites and use the scraped data within your business workflow, you can keep using the same system for many years. How to Scrape a Websites' Data With Beautiful Soup Now that you have everything up and ready, open up a preferred code editor and create a new Python file, giving it a chosen name. However, you can also make use of web-based IDEs like Jupyter Notebook if you're not familiar with running Python via the command line.
- Python Web Scraping Resources
- Selected Reading
In the previous chapter, we have seen scraping dynamic websites. In this chapter, let us understand scraping of websites that work on user based inputs, that is form based websites.
Introduction
These days WWW (World Wide Web) is moving towards social media as well as usergenerated contents. So the question arises how we can access such kind of information that is beyond login screen? For this we need to deal with forms and logins.
In previous chapters, we worked with HTTP GET method to request information but in this chapter we will work with HTTP POST method that pushes information to a web server for storage and analysis.
Interacting with Login forms
While working on Internet, you must have interacted with login forms many times. They may be very simple like including only a very few HTML fields, a submit button and an action page or they may be complicated and have some additional fields like email, leave a message along with captcha for security reasons.
In this section, we are going to deal with a simple submit form with the help of Python requests library.
First, we need to import requests library as follows −
Now, we need to provide the information for the fields of login form.
In next line of code, we need to provide the URL on which action of the form would happen.
After running the script, it will return the content of the page where action has happened.
Suppose if you want to submit any image with the form, then it is very easy with requests.post(). You can understand it with the help of following Python script −
Loading Cookies from the Web Server
A cookie, sometimes called web cookie or internet cookie, is a small piece of data sent from a website and our computer stores it in a file located inside our web browser.
In the context of dealings with login forms, cookies can be of two types. One, we dealt in the previous section, that allows us to submit information to a website and second which lets us to remain in a permanent “logged-in” state throughout our visit to the website. For the second kind of forms, websites use cookies to keep track of who is logged in and who is not.
What do cookies do?
These days most of the websites are using cookies for tracking. We can understand the working of cookies with the help of following steps −
Step 1 − First, the site will authenticate our login credentials and stores it in our browser’s cookie. This cookie generally contains a server-generated toke, time-out and tracking information.
Step 2 − Next, the website will use the cookie as a proof of authentication. This authentication is always shown whenever we visit the website.
Cookies are very problematic for web scrapers because if web scrapers do not keep track of the cookies, the submitted form is sent back and at the next page it seems that they never logged in. It is very easy to track the cookies with the help of Python requests library, as shown below −
In the above line of code, the URL would be the page which will act as the processor for the login form.
After running the above script, we will retrieve the cookies from the result of last request.
There is another issue with cookies that sometimes websites frequently modify cookies without warning. Such kind of situation can be dealt with requests.Session() as follows −
In the above line of code, the URL would be the page which will act as the processor for the login form.
Observe that you can easily understand the difference between script with session and without session.
Automating forms with Python
In this section we are going to deal with a Python module named Mechanize that will reduce our work and automate the process of filling up forms.
Free Web Scraper
Mechanize module
Mechanize module provides us a high-level interface to interact with forms. Before starting using it we need to install it with the following command −
Note that it would work only in Python 2.x.
Sites For Web Scraping And Data
Example
In this example, we are going to automate the process of filling a login form having two fields namely email and password −
Sites For Web Scraping Software
The above code is very easy to understand. First, we imported mechanize module. Then a Mechanize browser object has been created. Then, we navigated to the login URL and selected the form. After that, names and values are passed directly to the browser object.