Released:
Mar 18, 2021 Web scraping with Python is easy due to the many useful libraries available. A barebones installation isn’t enough for web scraping. One of the Python advantages is a large selection of libraries for web scraping. For this Python web scraping tutorial, we’ll be using three important libraries – BeautifulSoup v4, Pandas, and Selenium. Web scraping is a complex task and the complexity multiplies if the website is dynamic. According to United Nations Global Audit of Web Accessibility more than 70% of the websites are dynamic in nature and they rely on JavaScript for their functionalities.
Web scraping with Python is easy due to the many useful libraries available. A barebones installation isn’t enough for web scraping. One of the Python advantages is a large selection of libraries for web scraping. For this Python web scraping tutorial, we’ll be using three important libraries – BeautifulSoup v4, Pandas, and Selenium. One of the coolest code editors available to programmers, Visual Studio Code, is an open-source, extensible, light-weight editor available on all platforms.It’s these qualities that make Visual Studio Code from Microsoft very popular, and a great platform for Python development. Let’s say you are working on a project that needs to do web scraping but you don’t know websites on which scraping is to be performed beforehand instead you are required to perform google search and then proceed according to google search result to few websites. In that case you need google search result for your different queries.
A python library to search keyword on google and scrape search results data.
Project description
Google-Search-Scraper-Python is a python library to search keyword on google and fetch search results using browser automation.It currently runs only on windows.
Example 1
In this example we first import library, then we search a keyword and fetched results.
Example 2
In this example we first import library, then we search a keyword in images and fetched results.
This module depends on the following python modules
BotStudio
bot_studio is needed for browser automation. As soon as this library is imported in code, automated browser will open up in which search will be done.
Complete documentation for Google Automation available here
Installation
Import
Search a keyword
Search a keyword on images
Get search results
Get search image results
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In the last tutorial we learned how to leverage the Scrapy framework to solve common web scraping problems.Today we are going to take a look at Selenium (with Python ❤️ ) in a step-by-step tutorial.
Selenium refers to a number of different open-source projects used for browser automation. It supports bindings for all major programming languages, including our favorite language: Python.
The Selenium API uses the WebDriver protocol to control a web browser, like Chrome, Firefox or Safari. The browser can run either localy or remotely.
At the beginning of the project (almost 20 years ago!) it was mostly used for cross-browser, end-to-end testing (acceptance tests).
Now it is still used for testing, but it is also used as a general browser automation platform. And of course, it us used for web scraping!
Selenium is useful when you have to perform an action on a website such as:
- Clicking on buttons
- Filling forms
- Scrolling
- Taking a screenshot
It is also useful for executing Javascript code. Let's say that you want to scrape a Single Page Application. Plus you haven't found an easy way to directly call the underlying APIs. In this case, Selenium might be what you need.
Installation
We will use Chrome in our example, so make sure you have it installed on your local machine:
selenium
package
To install the Selenium package, as always, I recommend that you create a virtual environment (for example using virtualenv) and then:
Quickstart
Once you have downloaded both Chrome and Chromedriver and installed the Selenium package, you should be ready to start the browser:
This will launch Chrome in headfull mode (like regular Chrome, which is controlled by your Python code).You should see a message stating that the browser is controlled by automated software.
To run Chrome in headless mode (without any graphical user interface), you can run it on a server. See the following example:
The driver.page_source
will return the full page HTML code.
Here are two other interesting WebDriver properties:
driver.title
gets the page's titledriver.current_url
gets the current URL (this can be useful when there are redirections on the website and you need the final URL)
Locating Elements
Locating data on a website is one of the main use cases for Selenium, either for a test suite (making sure that a specific element is present/absent on the page) or to extract data and save it for further analysis (web scraping).
There are many methods available in the Selenium API to select elements on the page. You can use:
- Tag name
- Class name
- IDs
- XPath
- CSS selectors
We recently published an article explaining XPath. Don't hesitate to take a look if you aren't familiar with XPath.
As usual, the easiest way to locate an element is to open your Chrome dev tools and inspect the element that you need.A cool shortcut for this is to highlight the element you want with your mouse and then press Ctrl + Shift + C or on macOS Cmd + Shift + C instead of having to right click + inspect each time:
find_element
There are many ways to locate an element in selenium.Let's say that we want to locate the h1 tag in this HTML:
All these methods also have find_elements
(note the plural) to return a list of elements.
For example, to get all anchors on a page, use the following:
Some elements aren't easily accessible with an ID or a simple class, and that's when you need an XPath expression. You also might have multiple elements with the same class (the ID is supposed to be unique).
XPath is my favorite way of locating elements on a web page. It's a powerful way to extract any element on a page, based on it's absolute position on the DOM, or relative to another element.
WebElement
A WebElement
is a Selenium object representing an HTML element.
There are many actions that you can perform on those HTML elements, here are the most useful:
- Accessing the text of the element with the property
element.text
- Clicking on the element with
element.click()
- Accessing an attribute with
element.get_attribute('class')
- Sending text to an input with:
element.send_keys('mypassword')
There are some other interesting methods like is_displayed()
. This returns True if an element is visible to the user.
It can be interesting to avoid honeypots (like filling hidden inputs).
Honeypots are mechanisms used by website owners to detect bots. For example, if an HTML input has the attribute type=hidden
like this:
This input value is supposed to be blank. If a bot is visiting a page and fills all of the inputs on a form with random value, it will also fill the hidden input. A legitimate user would never fill the hidden input value, because it is not rendered by the browser.
That's a classic honeypot.
Full example
Here is a full example using Selenium API methods we just covered.
We are going to log into Hacker News:
In our example, authenticating to Hacker News is not really useful on its own. However, you could imagine creating a bot to automatically post a link to your latest blog post.
In order to authenticate we need to:
- Go to the login page using
driver.get()
- Select the username input using
driver.find_element_by_*
and thenelement.send_keys()
to send text to the input - Follow the same process with the password input
- Click on the login button using
element.click()
Should be easy right? Let's see the code:
Easy, right? Now there is one important thing that is missing here. How do we know if we are logged in?
We could try a couple of things:
- Check for an error message (like “Wrong password”)
- Check for one element on the page that is only displayed once logged in.
So, we're going to check for the logout button. The logout button has the ID “logout” (easy)!
We can't just check if the element is None
because all of the find_element_by_*
raise an exception if the element is not found in the DOM.So we have to use a try/except block and catch the NoSuchElementException
exception:
Taking a screenshot
We could easily take a screenshot using:
Note that a lot of things can go wrong when you take a screenshot with Selenium. First, you have to make sure that the window size is set correctly.Then, you need to make sure that every asynchronous HTTP call made by the frontend Javascript code has finished, and that the page is fully rendered.
In our Hacker News case it's simple and we don't have to worry about these issues.
Waiting for an element to be present
Dealing with a website that uses lots of Javascript to render its content can be tricky. These days, more and more sites are using frameworks like Angular, React and Vue.js for their front-end. These front-end frameworks are complicated to deal with because they fire a lot of AJAX calls.
If we had to worry about an asynchronous HTTP call (or many) to an API, there are two ways to solve this:
- Use a
time.sleep(ARBITRARY_TIME)
before taking the screenshot. - Use a
WebDriverWait
object.
If you use a time.sleep()
you will probably use an arbitrary value. The problem is, you're either waiting for too long or not enough.Also the website can load slowly on your local wifi internet connection, but will be 10 times faster on your cloud server.With the WebDriverWait
method you will wait the exact amount of time necessary for your element/data to be loaded.
This will wait five seconds for an element located by the ID “mySuperId” to be loaded.There are many other interesting expected conditions like:
element_to_be_clickable
text_to_be_present_in_element
element_to_be_clickable
You can find more information about this in the Selenium documentation
Executing Javascript
Sometimes, you may need to execute some Javascript on the page. For example, let's say you want to take a screenshot of some information, but you first need to scroll a bit to see it.You can easily do this with Selenium:
Conclusion
Python Web Scraping Search Results Online
I hope you enjoyed this blog post! You should now have a good understanding of how the Selenium API works in Python. If you want to know more about how to scrape the web with Python don't hesitate to take a look at our general Python web scraping guide.
Selenium is often necessary to extract data from websites using lots of Javascript. The problem is that running lots of Selenium/Headless Chrome instances at scale is hard. This is one of the things we solve with ScrapingBee, our web scraping API
Selenium is also an excellent tool to automate almost anything on the web.
Scrapy
If you perform repetitive tasks like filling forms or checking information behind a login form where the website doesn't have an API, it's maybe* a good idea to automate it with Selenium,just don't forget this xkcd: