error switching to iframe selenium python

Question

Currently I'm attempting to switch to iframe/fancybox, but i'm getting the following error:

line 237, in check_response raise exception_class
(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: 
Message: unknown error: missing 'ELEMENT'

This is how I'm locating the iframe:

_iframe_ = {"by": By.XPATH, "value": "//iframe[@class='fancybox-iframe' and starts-with(@id,'fancybox-frame') and contains(@src,'/reminder/add/relation/')]"}


 def __init__(self, driver):
        super(BasePage, self).__init__()
        self.driver = drive
        self.driver.switch_to.frame(self._iframe_)

iframe name is:

fancybox-frame1518441842751" 

html:

  <iframe id="fancybox-frame1518443041369" name="fancybox-frame1518443041369" class="fancybox-iframe" frameborder="0" vspace="0" hspace="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen="" scrolling="auto" src="/reminder/add/relation/58048" kwframeid="1"></iframe>

Answer 1

The id and name attributes looks dynamic (the number doesn't match in the code and html). You can try to locate by partial id/name

_iframe_ = {"by": By.CSS_SELECTOR, "value": "[id*='fancybox-frame']"}
# "[name*='fancybox-frame']"

As a side note, frame() can receive id/name as parameter

self.driver.switch_to.frame('fancybox-frame1518441842751')

Would have worked (except for the dynamic issue of course).

Answer 2

To identify the <iframe> properly you have to change the Locator Strategy as follows :

_iframe_ = {"by": By.XPATH, "value": "//iframe[@class='fancybox-iframe' and starts-with(@id,'fancybox-frame') and contains(@src,'/reminder/add/relation/')]"}

 def __init__(self, driver):
    super(BasePage, self).__init__()
    self.driver = driver
    WebDriverWait(driver, 10).until(EC.frame_to_be_available_and_switch_to_it((self._iframe_)))