Help to get dynamic value created with javascript in Python

Luca Simonetti

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Nov 29, 2015, 1:05:49 AM11/29/15

to Selenium Users

Hi everybody,

I'm getting crazy trying to find out how to get a element value from a javascript dynamic generated page:
Following is the html code for the element that I'm trying to get:

<td>

</td>

This is my pytnon code:

from selenium import webdriver
from selenium.common.exceptions import TimeoutException
from selenium.webdriver.firefox.firefox_binary import FirefoxBinary
from selenium.webdriver.support.ui import WebDriverWait # available since 2.4.0
from selenium.webdriver.support import expected_conditions as EC # available since 2.26.0

# Create new istance of Firefox driver
binary = FirefoxBinary('/Applications/Programmi/Internet/Firefox.app/Contents/MacOS/firefox')
driver = webdriver.Firefox(firefox_binary=binary)
print ('creata istanza webdriver')

# Goto URL
driver.get('http://xxx.xxx.xxx.x/page1.htm')

# Print title
print 'Titolo pagina: '
print driver.title

# find the element that's name attribute is t08451 ovvero EVC AO04 Enjector Control
driver.implicitly_wait(10) # seconds
element = driver.find_element_by_name("t08451") # it works same way with by ID locator
print 'element: '
print element

driver.implicitly_wait(10) # seconds

element_value = element.get_attribute('value')

print 'Value: '
print element_value

driver.quit()

and this is the output of the script:

$ python2.7 ./sel_fire.py
creata istanza webdriver
Titolo pagina:
I/O
element:
<selenium.webdriver.remote.webelement.WebElement (session="c5644dcd-5566-c942-9d00-0ce99be37f11", element="{c8a361ee-02ef-5a4c-ba9f-cf9ee34c94b5}")>
Value:

$

As you can see I receive back a blank value. I've also tried to use the driver.execute_script method with no solution, but any help will be appreciate.

Thanks in advance.
Luca

PeterJeffreyGale

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Nov 29, 2015, 1:34:55 PM11/29/15

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The default element value looks to be set to 'blank':

If you are expecting the 'value'attribute to get updated by the javascript embedded in this elelemt:

... it only seems to update the 'value' attribute in response to keystrokes (I think), and I can't see that your script has done anything to change the default value.

So what value are you expecting to get returned? And why?

Luca Simonetti

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Nov 30, 2015, 3:37:40 AM11/30/15

to Selenium Users

First of all, thanks PeterJeffreyGale,

the element value that I'm trying to read on the browser appears as soon as I load the page. That page contains values of variables from a industrial machine and I need to record some of those values.

On Firefox as soon as I load the page the elements are displayed, so I'm expecting to read my element after raws

driver.get('http://xxx.xxx.xxx.xxx/page1.htm')

# Print title
print 'Titolo pagina: '
print driver.title

# find the element that's name attribute is t08451 ovvero EVC AO04 Enjector Control

element = driver.find_element_by_name("t08451")

time.sleep(0.2) # Let the page load
print 'element: '
print element

time.sleep(0.2) # Let the page load

element_value = element.get_attribute('value')

print 'Value: '
print element_value

Moreover I tried to use the Selenium IDE Firefox plugin and inside it I am able to read that value with command "verifyValue" and in fact it returns the correct value; therefore I do not understand how to to do the same with Python.
Maybe as you noticed I should try to issue a UI command like a "click" or other keystroke, I am going to try and I will let you know. However if you or some else have some more suggestions I will appreciate.

Luca

Luca Simonetti

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Dec 1, 2015, 3:03:17 AM12/1/15

to Selenium Users

Hi there,
let me public how I solved my little problem:
thanks to the suggestion of PeterJeffreyGale I added some lines of code to trigger an event on the page from where I'm trying to read data:

from selenium import webdriver
from selenium.common.exceptions import TimeoutException
from selenium.webdriver.firefox.firefox_binary import FirefoxBinary

from selenium.webdriver.firefox.firefox_profile import FirefoxProfile

from selenium.webdriver.support.ui import WebDriverWait # available since 2.4.0
from selenium.webdriver.support import expected_conditions as EC # available since 2.26.0

from selenium.webdriver.common.action_chains import ActionChains #to use action like click
from selenium.webdriver.support.ui import WebDriverWait

# Create new istance of Firefox driver
binary = FirefoxBinary('/Applications/Programmi/Internet/Firefox.app/Contents/MacOS/firefox')
driver = webdriver.Firefox(firefox_binary=binary)

# Goto URL
driver.get('http://xxx.xxx.xxx.xxx/page1.htm') # IP addr is intentionally masqueraded

#find the element that's name attribute is t08451

element = driver.find_element_by_name("t08451")

time.sleep(0.2)                                                                                               # Wait 2 milliseconds

Hover = ActionChains(driver).move_to_element(element)                            #
Hover.click()                                                                                                   # these three lines make the magic to trigger a click on my element
Hover.perform()                                                                                              #
element.click()                                                                                                #

time.sleep(0.5)                                                                                                # Wait 0.5 seconds

element_value = element.get_attribute('value')

print 'Value V: '
print element_value

driver.quit()

and below you can see the output of the script containing my valeu from the page:

$ python2.7 ./sel_fire.py
Value V:
50.0
$

Once again thanks to PeterJeffreyGale

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