nonshatter nonshatter -4 years ago 166
Python Question

Python - Selenium WebDriver - Checking element exists

I have a problem - I am using the selenium (firefox) web driver to open a webpage, click a few links etc. then capture a screenshot.

My script runs fine from the CLI, but when run via a cronjob it is not getting past the first find_element() test. I need to add some debug, or something to help me figure out why it is failing.

Basically, I have to click a 'log in' anchor before going to the login page. The construct of the element is:

<a class="lnk" rel="nofollow" href="/login.jsp?destination=/secure/Dash.jspa">log in</a>

I am using the find_element By LINK_TEXT method:

login = driver.find_element(By.LINK_TEXT, "log in").click()

I am a bit of a Python Noob, so I am battling with the language a bit...

A) How do I check that the link is actually being picked up by python? Should I use try/catch block?

B) Is there a better/more reliable way to locate the DOM element than by LINK_TEXT? E.g. In JQuery, you can use a more specific selector $('a.lnk:contains(log in)').do_something();

I have solved the main problem and it was just finger trouble - I was calling the script with incorrect parameters - Simple mistake.

I'd still like some pointers on how to check whether an element exists. Also, an example/explanation of implicit / explicit Waits instead of using a crappy time.sleep() call.

Cheers, ns

Answer Source

A) Yes. The easiest way to check if an element exists is to simply call find_element inside a try/catch.

B) Yes, I always try to identify elements without using their text for 2 reasons:

  1. the text is more likely to change and;
  2. if it is important to you, you won't be able to run your tests against localized builds.

solution either:

  1. You can use xpath to find a parent or ancestor element that has an ID or some other unique identifier and then find it's child/descendant that matches or;
  2. you could request an ID or name or some other unique identifier for the link itself.

For the follow up questions, using try/catch is how you can tell if an element exists or not and good examples of waits can be found here:

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