Selenium - unable to find element- during second time - selenium

Question

I am trying to find element like this -
Select servTypeDA = new Select (driver.findElement(By.xpath("//select[#id='ServicesType']")));
servTypeDA.selectByVisibleText(servTypeData);
This works fine perfectly for the first time, when I load this page.
I am trying to do a workflow so when this page loads after couple of steps, for the same line it throws the error -
org.openqa.selenium.NoSuchElementException: Unable to locate element
But I am able to see the element in the screen and its visible but still not accessible by code.
I tried to add wait time, still throws error.
Why the same element is not accessible for the second time?

Answer 1

NoSuchElement is thrown when webdriver is not able to find the element in DOM. The main cause of this is probaly you are searching for the element too early. I would suggest to use some explicit wait and do a check for the element with regular interval.
By byXpath = By.xpath("//select[#id='ServicesType']");
WebElement element = new WebDriverWait(driver,10).until(ExpectedConditions.visibilityOfElementLocated(byXpath));
Select servTypeDA = new Select(element);
servTypeDA.selectByVisibleText(servTypeData);

Answer 2

Or you can set implicitlyWait which is by default 0.
By setting this, Webdriver will wait for given amount of time before throwing NoSuchElementException
driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
It will save your effort of adding webdriverWait almost before each Element.

Answer 3

The way that webdriver works is that each page load it copies the page. So what is shown does not have to be what is loaded in the webdriver instance. For example if you change the webpage via JavaScript, the webdriver would not be aware of it.
These often is the couse for
NoSuchElementException
or
StaleElementReferenceException
I found that the only cure for this is to catch the exception and try again. I had to create a new function for each type of action. I will show you my example for "selectByVisibleText"
public void selectByLabel(final By by, final String label){
act(by, 3, new Callable<Boolean>() {
public Boolean call() {
logger.trace("Trying to select label: "+label+" in select box "+stripBy(by) );
Boolean found = Boolean.FALSE;
int attempts = 0;
wait.until(ExpectedConditions.refreshed(ExpectedConditions.elementToBeClickable(by)));
Select select = new Select(driver.findElement(by));
select.selectByVisibleText(label);
if(isLabelSelected(by,label)){
found = Boolean.TRUE; // FOUND IT
logger.info("Selected value "+label+" in select box "+stripBy(by));
}
return found;
}
});
}
It will retry for a few times.
All my special implementetation of action use a function for catching exceptions
private void act(By by, int tryLimit, boolean mode, Callable<Boolean> method){
logger.trace( "Looking for element: " + stripBy(by) );
driver.manage().timeouts().implicitlyWait( 5, TimeUnit.SECONDS );
boolean unfound = true;
int tries = 0;
while ( unfound && tries < tryLimit ) {
tries += 1;
try {
WebDriverWait wait = new WebDriverWait(driver, 500);
unfound = !method.call(); // FOUND IT, this is negated since it feel more intuitive if the call method returns true for success
} catch ( StaleElementReferenceException ser ) {
logger.error( "ERROR: Stale element exception. " + stripBy(by) );
unfound = true;
} catch ( NoSuchElementException nse ) {
logger.error( "ERROR: No such element exception. " + stripBy(by)+"\nError: "+nse );
unfound = true;
} catch ( Exception e ) {
logger.error( e.getMessage() );
}
}
driver.manage().timeouts().implicitlyWait( Constants.DEFAULT_IMPLICIT_WAIT, TimeUnit.SECONDS );
if(unfound)
Assert.assertTrue(false,"Failed to locate element by locator " + stripBy(by));
}