selenium set attribute - http://stackoverflow.com/questions/25583641/set-value-of-input-instead-of-sendkeys-selenium-webdriver-nodejs

selenium_set_attribute.py

# retrieve webelement
input = driver.find_element_by_xpath("//*[@name='fieldname']")
# set attribute from js script referencing webelement found in python code
driver.execute_script("arguments[0].setAttribute('value', 'new value!')", input);
# or
driver.execute_script("arguments[0].setAttribute('value', arguments[1])", input, 'new value!');

# Code for File Upload
file_input = driver.find_element_by_id("uploadBtn")
file_input.send_keys("/absolute/path/to/file")