python selenium webscraping “NoSuchElementExceptio

Sometimes on a page I'll be looking for an element which may or may not be there. I wanted to try/catch this case with a NoSuchElementException, which selenium was throwing when certain HTML elements didn't exist. Original exception:

NoSuchElementException: Message: u'Unable to locate element: {"method":"css selector","selector":"#one"}' ; Stacktrace: 
    at FirefoxDriver.prototype.findElementInternal_ (file:///var/folders/6q/7xcjtgyj32nfc2yp_y5tr9pm0000gn/T/tmp63Mz2a/extensions/fxdriver@googlecode.com/components/driver_component.js:8899)
    at FirefoxDriver.prototype.findChildElement (file:///var/folders/6q/7xcjtgyj32nfc2yp_y5tr9pm0000gn/T/tmp63Mz2a/extensions/fxdriver@googlecode.com/components/driver_component.js:8911)
    at DelayedCommand.prototype.executeInternal_/h (file:///var/folders/6q/7xcjtgyj32nfc2yp_y5tr9pm0000gn/T/tmp63Mz2a/extensions/fxdriver@googlecode.com/components/command_processor.js:10840)
    at DelayedCommand.prototype.executeInternal_ (file:///var/folders/6q/7xcjtgyj32nfc2yp_y5tr9pm0000gn/T/tmp63Mz2a/extensions/fxdriver@googlecode.com/components/command_processor.js:10845)
    at DelayedCommand.prototype.execute/< (file:///var/folders/6q/7xcjtgyj32nfc2yp_y5tr9pm0000gn/T/tmp63Mz2a/extensions/fxdriver@googlecode.com/components/command_processor.js:10787)

Ironically, it won't let me catch this exception which it was throwing before? Code here:

elt = driver.find_element_by_css_selector('.information')
try:
    dat1 = elt.find_element_by_css_selector('#one').text
    dat2 = elt.find_elements_by_css_selector('#two')[1].text
    text = dat1 + dat2
except NoSuchElementException:
    text = elt.find_element_by_css_selector('#all').text
    item.set_description(text)

Error here:

NameError: name 'NoSuchElementException' is not defined

Googling/documentation came up with nothing...and it strikes me as strange that selenium is fine throwing an exception but can't catch it.

回答1:

You need to import the exception first

from selenium.common.exceptions import NoSuchElementException

and then you can reference it

except NoSuchElementException:
    # handle the element not existing

回答2:

You sould use from selenium.common.exceptions import * and then write except NoSuchElementException