5 Best Ways to Check if an Element Exists with Python Selenium

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πŸ’‘ Problem Formulation: When automating web browser interactions using Python Selenium, detecting the presence or absence of web elements on a webpage is crucial for writing robust scripts. The challenge lies in correctly confirming whether an element exists without triggering exceptions or false negatives. Typically, a user might input a selector like css_selector, xpath, id etc., and expect a boolean output indicating the element’s existence.

Method 1: Using find_element_by methods

This is the most straightforward method where specific find_element_by functions provided by Selenium WebDriver are used to retrieve an element. If the element is not found, a ‘NoSuchElementException’ is raised.

Here’s an example:

from selenium import webdriver
from selenium.common.exceptions import NoSuchElementException

driver = webdriver.Chrome()
driver.get("https://www.example.com")

try:
    element = driver.find_element_by_id("nonexistent-id")
    exists = True
except NoSuchElementException:
    exists = False

print(exists)

Output: False

This code tries to find an element by its ID. If the element is not present on the page, a NoSuchElementException is caught, and the existence flag is set to False.

Method 2: Using the presence_of_element_located condition from expected_conditions

The Expected Conditions helper functions within Selenium’s support module offer a more elegant way to wait for conditions to be fulfilled, including checking for an element’s presence.

Here’s an example:

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

driver = webdriver.Chrome()
driver.get("https://www.example.com")
locator = (By.ID, "nonexistent-id")

exists = WebDriverWait(driver, 10).until(EC.presence_of_element_located(locator))
print(exists)

Output: TimeoutException (after 10 seconds)

The code uses a WebDriverWait object to wait for up to 10 seconds for the specified element to become present. If the element does not exist, a TimeoutException will be thrown and caught.

Method 3: Checking element presence by find_elements_by methods

Instead of catching exceptions, you can use the find_elements_by methods which return a list of elements. If the list is empty, the element was not found.

Here’s an example:

from selenium import webdriver

driver = webdriver.Chrome()
driver.get("https://www.example.com")

elements = driver.find_elements_by_id("nonexistent-id")
exists = len(elements) > 0

print(exists)

Output: False

This snippet tries to find all elements on the page with the given ID. If no elements are found, the length of the returned list is zero, indicating the element does not exist.

Method 4: Using is_displayed()

The is_displayed() method is used after an element is found to check if it is visible to the user. If the element is not found, you will encounter a ‘NoSuchElementException’.

Here’s an example:

from selenium import webdriver
from selenium.common.exceptions import NoSuchElementException

driver = webdriver.Chrome()
driver.get("https://www.example.com")

try:
    element = driver.find_element_by_id("nonexistent-id")
    exists = element.is_displayed()
except NoSuchElementException:
    exists = False

print(exists)

Output: False

In this example, the script first tries to find the element, then checks if it is displayed, which would return True or False. If the element cannot be found, an exception is caught and False is returned.

Bonus One-Liner Method 5: Using Implicit Waits

Selenium WebDriver can be configured to poll the DOM for a certain duration until elements are found, known as implicit waits. Although using them is not recommended as they may lead to flaky tests, they serve as a one-liner solution for element existence check.

Here’s an example:

from selenium import webdriver

driver = webdriver.Chrome()
driver.implicitly_wait(10)  # Wait up to 10 seconds for elements to appear
driver.get("https://www.example.com")

exists = len(driver.find_elements_by_id("nonexistent-id")) > 0
print(exists)

Output: False

The code configures Selenium to wait up to 10 seconds for an element to become present. If the element is not found after 10 seconds, it returns False.

Summary/Discussion

Each of the methods for checking elements’ existence in Selenium have their pros and cons. Here’s a summary:

  • Method 1: Using find_element_by methods. Straightforward. Raises exceptions for non-existent elements. Can clutter code with try/except blocks.
  • Method 2: Using the presence_of_element_located condition. Elegant and self-explanatory. Relies on explicit waits that can delay the tests.
  • Method 3: Checking element presence by find_elements_by_methods. No exception handling needed. Can be less intuitive than using direct presence checks.
  • Method 4: Using is_displayed(). Checks visibility, not just presence. Can be misleading if element exists but is not visible.
  • Bonus Method 5: Using Implicit Waits. Simplifies syntax. Promotes bad practice and may lead to flakier tests.