Selenium WebDriver generates StaleElementReferenceExeption on getText() on table elements - selenium

Question

The current environment:
Selenium Server version 2.37.0
RemoteWebDriver running on Firefox
no Ajax / asynchronously loaded content
My tests are attempting to validate the content of each cell of an HTML table. Before accessing any table element an explicit wait verifies that the <tbody> element exists
ExpectedCondition<WebElement> recruitTableIsPresent = ExpectedConditions.presenceOfElementLocated(By.id("newRecruitFieldAgentWidget:newRecruitDataTable_data"));
new WebDriverWait(driver, 5).until(recruitTableIsPresent);
Once the table is verified to exist, data is pulled out by row and column
private Stats[] parseStats() {
String xpath = "//tbody[#id='regionalFieldAgentWidget:regionalDataTable_data']/tr[%d]/td[%d]";
Stats[] stats = new Stats[3];
for (int i = 0; i < stats.length; i++) {
String inProgresOrders = cellContent(xpath, i, 1);
String maxCapacity = cellContent(xpath, i, 2);
String allocationRatio = cellContent(xpath, i, 3);
Stats[i] = new Stats(inProgressORders, maxCapacity, allocationRatio);
}
return stats;
}
private String cellContent(String xpathTemplate, int row, int cell) {
String xpath = String.format(xpathTemplate, row + 1, cell + 1);
new WebDriverWait(driver, 10).until(ExpectedConditions.presenceOfElementLocated(By.xpath(xpath)));
WebElement elementByXPath = driver.findElementByXPath(xpath);
return elementByXPath.getText();
}
I don't see any race conditions, since the table content is populated with the page, and not in an asynchronous call. Additionally, I have seen other answers that suggest invoking findElement() via the driver instance will refresh the cache. Lastly, the explicit wait before accessing the element should ensure that the <TD> tag is present.
What could be causing the getText() method return the following exception:
org.openqa.selenium.StaleElementReferenceException: Element not found in the cache - perhaps the page has changed since it was looked up
It's worthwhile to note that the failure is intermittent. Some executions fail while other passes through the same code pass. The table cell causing the failure are also not consistent.

Answer 1

There is a solution to this using Html-Agility-Pack.
This will work only if you want to read the data from that page.
This goes likes this
//Convert the pageContent into documentNode.
void _getHtmlNode(IWebDriver driver){
var htmlDocument = new HtmlDocument();
htmlDocument.LoadHtml(driver.PageSource);
return htmlDocument.DocumentNode;
}
private Stats[] parseStats(){
String xpath = "//tbody[#id='regionalFieldAgentWidget:regionalDataTable_data']/tr[%d]/td[%d]";
Stats[] stats = new Stats[3];
for (int i = 0; i < stats.Length; i++) {
String inProgresOrders = cellContent(xpath, i, 1);
String maxCapacity = cellContent(xpath, i, 2);
String allocationRatio = cellContent(xpath, i, 3);
Stats[i] = new Stats(inProgressORders, maxCapacity, allocationRatio);
}
return stats;
}
private String cellContent(String xpathTemplate, int row, int cell) {
String xpath = String.format(xpathTemplate, row + 1, cell + 1);
new WebDriverWait(driver, 10).until(ExpectedConditions.presenceOfElementLocated(By.xpath(xpath)));
var documentNode = _getHtmlNode(driver);
var elementByXPath = documentNode.SelectSingleNode(xpath);
return elementByXPath.InnerText;
}
now read any data.
Some tips for using htmlNode.
1. Similar to driver.FindElement: document.SelectSingleNode
2. Similar to driver.FindElements: document.SelectNodes
3. Similar to driver.Text: document.InnerText.
For more search regarding HtmlNode.

Answer 2

Turns out there was a race condition as I've already mentioned. Since jQuery is available via PrimeFaces there is a very handy solution mentioned in a few other posts. I implemented the following method to wait for any asynchronous requests to return before parsing page elements
public static void waitForPageLoad(JavascriptExecutor jsContext) {
while (getActiveConnections(jsContext) > 0) {
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
throw new RuntimeException(ex);
}
}
}
private static long getActiveConnections(JavascriptExecutor jsContext) {
return (Long) jsContext.executeScript("return (window.jQuery || { active : 0 }).active");
}
Each built in driver implementation implements the JavascriptExecutor interface, so the calling code is very straightforward:
WebDriver driver = new FirefoxDriver();
waitForPageLoad((JavascriptExecutor) driver);