Explicit wait for Selenium Webdriver - ruby

Question

Working on the method trying to understand the explicit wait.
require 'rubygems'
require 'selenium-webdriver'
require 'cucumber'
$driver = Selenium::WebDriver.for :firefox
$driver.manage.timeouts.implicit_wait = 3
Then /^do search$/ do
driver = $driver
one_way = driver.find_element(:id, "search.ar.type.code.oneWay").click
sleep 5
from = driver.find_element :xpath => "//div[#class = 'origin column1']//input[#type = 'text']"
from.click
So after one_way radio button is clicked and input form changed , so I put sleep 5 to give it a time element to appear, otherwise would be error "element not visible ...". So I thought it would be good time to understand explicit wait, because I need to wait till element will appear.
wait = Selenium::WebDriver::Wait.new(:timeout => 40)
wait.until {from = driver.find_element(:xpath, "//div[#class = 'origin column1']//input[#type = 'text']")
from.click
}
But getting error "Selenium::WebDriver::Error::ElementNotVisibleError: Element is not currently visible and so may not be interacted with" . Why this code doesn't wait till element appears and click it?

Answer 1

The issue is that the element isn't in the DOM yet, hence your needing to put a time delay in there.
That said, the API doco for ruby says you should do it this way
require 'rubygems' # not required for ruby 1.9 or if you installed without gem
require 'selenium-webdriver'
driver = Selenium::WebDriver.for :firefox
driver.get "http://somedomain/url_that_delays_loading"
wait = Selenium::WebDriver::Wait.new(:timeout => 10) # seconds
begin
element = wait.until { driver.find_element(:id => "some-dynamic-element") }
ensure
driver.quit
end
note that the element that you can then .click() is assigned from the wait.until method not the find_element() method as in your code.
However that arbitrary delays don't always work, if the site is busy then the delay may not be long enough.
A better option is to wait for the element to become clickable or visible.
The Java API's have ExpectedConditions convenience methods that cn be used like this...
WebDriverWait wait = new WebDriverWait(driver, 10);
WebElement element = wait.until(ExpectedConditions.elementToBeClickable(By.id("someid")));
element.click();
Unfortunatly I don't think Ruby has this yet. You may need to code up your own ExpectedCondition class or package.
I'm not a Ruby dev but here is the idea of a function in Java that could be used to implement your ExpectedCondition
public WebElement findElementInTime(WebDriver driver, By by, int timeoutInSeconds)
{
log.debug("==================+>>>>>> looking for element for "+ timeoutInSeconds + " seconds");
WebElement ret = null;
for (int second = 0; second < timeoutInSeconds; second++) {
try { if (isElementPresent(driver,by)) {
log.debug("found element :-)");
ret = driver.findElement(by);
break;
}} catch (Exception e) {
log.debug("oops... sleeping 1 sec wait for button");
}
log.debug("sleeping 1 sec wait for button");
}
return ret;
}