java - 如何避免 Selenium 中的“StaleElementReferenceException”？

Question

我正在使用 Java 实现很多 Selenium 测试。有时，我的测试由于StaleElementReferenceException. 您能否提出一些使测试更稳定的方法？

score 109 · Accepted Answer

如果页面上发生的 DOM 操作暂时导致元素不可访问，则可能会发生这种情况。为了允许这些情况，您可以尝试在循环中多次访问该元素，然后最终引发异常。

试试这个来自 darrelgrainger.blogspot.com 的优秀解决方案：

public boolean retryingFindClick(By by) {
    boolean result = false;
    int attempts = 0;
    while(attempts < 2) {
        try {
            driver.findElement(by).click();
            result = true;
            break;
        } catch(StaleElementException e) {
        }
        attempts++;
    }
    return result;
}

score 73 · Accepted Answer

我间歇性地遇到这个问题。我不知道，BackboneJS 正在页面上运行并替换我试图单击的元素。我的代码看起来像这样。

driver.findElement(By.id("checkoutLink")).click();

这当然在功能上与此相同。

WebElement checkoutLink = driver.findElement(By.id("checkoutLink"));
checkoutLink.click();

偶尔会发生的是 javascript 会在查找和单击它之间替换 checkoutLink 元素，即。

WebElement checkoutLink = driver.findElement(By.id("checkoutLink"));
// javascript replaces checkoutLink
checkoutLink.click();

Which rightfully led to a StaleElementReferenceException when trying to click the link. I couldn't find any reliable way to tell WebDriver to wait until the javascript had finished running, so here's how I eventually solved it.

new WebDriverWait(driver, timeout)
    .ignoring(StaleElementReferenceException.class)
    .until(new Predicate<WebDriver>() {
        @Override
        public boolean apply(@Nullable WebDriver driver) {
            driver.findElement(By.id("checkoutLink")).click();
            return true;
        }
    });

This code will continually try to click the link, ignoring StaleElementReferenceExceptions until either the click succeeds or the timeout is reached. I like this solution because it saves you having to write any retry logic, and uses only the built-in constructs of WebDriver.

score 24 · Accepted Answer

Kenny's solution is good, however it can be written in a more elegant way

new WebDriverWait(driver, timeout)
        .ignoring(StaleElementReferenceException.class)
        .until((WebDriver d) -> {
            d.findElement(By.id("checkoutLink")).click();
            return true;
        });

Or also:

new WebDriverWait(driver, timeout).ignoring(StaleElementReferenceException.class).until(ExpectedConditions.elementToBeClickable(By.id("checkoutLink")));
driver.findElement(By.id("checkoutLink")).click();

But anyway, best solution is to rely on Selenide library, it handles this kind of things and more. (instead of element references it handles proxies so you never have to deal with stale elements, which can be quite difficult). Selenide

score 23 · Accepted Answer

通常这是由于 DOM 正在更新并且您尝试访问更新/新元素 - 但 DOM 已刷新，因此您拥有的引用无效..

通过首先在元素上使用显式等待以确保更新完成来解决此问题，然后再次获取对该元素的新引用。

这里有一些伪代码来说明（改编自我用于这个问题的一些 C# 代码）：

WebDriverWait wait = new WebDriverWait(browser, TimeSpan.FromSeconds(10));
IWebElement aRow = browser.FindElement(By.XPath(SOME XPATH HERE);
IWebElement editLink = aRow.FindElement(By.LinkText("Edit"));

//this Click causes an AJAX call
editLink.Click();

//must first wait for the call to complete
wait.Until(ExpectedConditions.ElementExists(By.XPath(SOME XPATH HERE));

//you've lost the reference to the row; you must grab it again.
aRow = browser.FindElement(By.XPath(SOME XPATH HERE);

//now proceed with asserts or other actions.

希望这可以帮助！

score 11 · Accepted Answer

The reason why the StaleElementReferenceException occurs has been laid out already: updates to the DOM between finding and doing something with the element.

For the click-Problem I've recently used a solution like this:

public void clickOn(By locator, WebDriver driver, int timeout)
{
    final WebDriverWait wait = new WebDriverWait(driver, timeout);
    wait.until(ExpectedConditions.refreshed(
        ExpectedConditions.elementToBeClickable(locator)));
    driver.findElement(locator).click();
}

The crucial part is the "chaining" of Selenium's own ExpectedConditions via the ExpectedConditions.refreshed(). This actually waits and checks if the element in question has been refreshed during the specified timeout and additionally waits for the element to become clickable.

Have a look at the documentation for the refreshed method.

score 4 · Accepted Answer

In my project I introduced a notion of StableWebElement. It is a wrapper for WebElement which is able to detect if element is Stale and find a new reference to the original element. I have added a helper methods to locating elements which return StableWebElement instead of WebElement and the problem with StaleElementReference disappeared.

public static IStableWebElement FindStableElement(this ISearchContext context, By by)
{
    var element = context.FindElement(by);
    return new StableWebElement(context, element, by, SearchApproachType.First);
}

The code in C# is available on my project's page but it could be easily ported to java https://github.com/cezarypiatek/Tellurium/blob/master/Src/MvcPages/SeleniumUtils/StableWebElement.cs

score 0 · Accepted Answer

A solution in C# would be:

Helper class:

internal class DriverHelper
{

    private IWebDriver Driver { get; set; }
    private WebDriverWait Wait { get; set; }

    public DriverHelper(string driverUrl, int timeoutInSeconds)
    {
        Driver = new ChromeDriver();
        Driver.Url = driverUrl;
        Wait = new WebDriverWait(Driver, TimeSpan.FromSeconds(timeoutInSeconds));
    }

    internal bool ClickElement(string cssSelector)
    {
        //Find the element
        IWebElement element = Wait.Until(d=>ExpectedConditions.ElementIsVisible(By.CssSelector(cssSelector)))(Driver);
        return Wait.Until(c => ClickElement(element, cssSelector));
    }

    private bool ClickElement(IWebElement element, string cssSelector)
    {
        try
        {
            //Check if element is still included in the dom
            //If the element has changed a the OpenQA.Selenium.StaleElementReferenceException is thrown.
            bool isDisplayed = element.Displayed;

            element.Click();
            return true;
        }
        catch (StaleElementReferenceException)
        {
            //wait until the element is visible again
            element = Wait.Until(d => ExpectedConditions.ElementIsVisible(By.CssSelector(cssSelector)))(Driver);
            return ClickElement(element, cssSelector);
        }
        catch (Exception)
        {
            return false;
        }
    }
}

Invocation:

        DriverHelper driverHelper = new DriverHelper("http://www.seleniumhq.org/docs/04_webdriver_advanced.jsp", 10);
        driverHelper.ClickElement("input[value='csharp']:first-child");

Similarly can be used for Java.

score 0 · Accepted Answer

Kenny's solution is deprecated use this, i'm using actions class to double click but you can do anything.

new FluentWait<>(driver).withTimeout(30, TimeUnit.SECONDS).pollingEvery(5, TimeUnit.SECONDS)
                    .ignoring(StaleElementReferenceException.class)
                    .until(new Function() {

                    @Override
                    public Object apply(Object arg0) {
                        WebElement e = driver.findelement(By.xpath(locatorKey));
                        Actions action = new Actions(driver);
                        action.moveToElement(e).doubleClick().perform();
                        return true;
                    }
                });

score 0 · Accepted Answer

I've found solution here. In my case element becomes inaccessible in case of leaving current window, tab or page and coming back again.

.ignoring(StaleElement...), .refreshed(...) and elementToBeClicable(...) did not help and I was getting exception on act.doubleClick(element).build().perform(); string.

Using function in my main test class:

openForm(someXpath);

My BaseTest function:

int defaultTime = 15;

boolean openForm(String myXpath) throws Exception {
    int count = 0;
    boolean clicked = false;
    while (count < 4 || !clicked) {
        try {
            WebElement element = getWebElClickable(myXpath,defaultTime);
            act.doubleClick(element).build().perform();
            clicked = true;
            print("Element have been clicked!");
            break;
        } catch (StaleElementReferenceException sere) {
            sere.toString();
            print("Trying to recover from: "+sere.getMessage());
            count=count+1;
        }
    }

My BaseClass function:

protected WebElement getWebElClickable(String xpath, int waitSeconds) {
        wait = new WebDriverWait(driver, waitSeconds);
        return wait.ignoring(StaleElementReferenceException.class).until(
                ExpectedConditions.refreshed(ExpectedConditions.elementToBeClickable(By.xpath(xpath))));
    }

score 0 · Accepted Answer

Clean `findByAndroidId` method that gracefully handles `StaleElementReference`.

This is heavily based off of jspcal's answer but I had to modify that answer to get it working cleanly with our setup and so I wanted to add it here in case it's helpful to others. If this answer helped you, please go upvote jspcal's answer.

// This loops gracefully handles StateElementReference errors and retries up to 10 times. These can occur when an element, like a modal or notification, is no longer available.
export async function findByAndroidId( id, { assert = wd.asserters.isDisplayed, timeout = 10000, interval = 100 } = {} ) {
  MAX_ATTEMPTS = 10;
  let attempt = 0;

  while( attempt < MAX_ATTEMPTS ) {
    try {
      return await this.waitForElementById( `android:id/${ id }`, assert, timeout, interval );
    }
    catch ( error ) {
      if ( error.message.includes( "StaleElementReference" ) )
        attempt++;
      else
        throw error; // Re-throws the error so the test fails as normal if the assertion fails.
    }
  }
}

score -1 · Accepted Answer

This works for me using C#

public Boolean RetryingFindClick(IWebElement webElement)
    {
        Boolean result = false;
        int attempts = 0;
        while (attempts < 2)
        {
            try
            {
                webElement.Click();
                result = true;
                break;
            }
            catch (StaleElementReferenceException e)
            {
                Logging.Text(e.Message);
            }
            attempts++;
        }
        return result;
    }

score -1 · Accepted Answer

The problem is by the time you pass the element from Javascript to Java back to Javascript it can have left the DOM.
Try doing the whole thing in Javascript:

driver.executeScript("document.querySelector('#my_id')?.click()")

score -1 · Accepted Answer

Try this

while (true) { // loops forever until break
    try { // checks code for exceptions
        WebElement ele=
        (WebElement)wait.until(ExpectedConditions.elementToBeClickable((By.xpath(Xpath))));  
        break; // if no exceptions breaks out of loop
    } 
    catch (org.openqa.selenium.StaleElementReferenceException e1) { 
        Thread.sleep(3000); // you can set your value here maybe 2 secs
        continue; // continues to loop if exception is found
    }
}

score -1 · Accepted Answer

There could be a potential problem that leads to the StaleElementReferenceException that no one mentioned so far (in regard to actions).

I explain it in Javascript, but it's the same in Java.

This won't work:

let actions = driver.actions({ bridge: true })
let a = await driver.findElement(By.css('#a'))
await actions.click(a).perform() // this leads to a DOM change, #b will be removed and added again to the DOM.
let b = await driver.findElement(By.css('#b'))
await actions.click(b).perform()

But instantiating the actions again will solve it:

let actions = driver.actions({ bridge: true })
let a = await driver.findElement(By.css('#a'))
await actions.click(a).perform()  // this leads to a DOM change, #b will be removed and added again to the DOM.
actions = driver.actions({ bridge: true }) // new
let b = await driver.findElement(By.css('#b'))
await actions.click(b).perform()

score -1 · Accepted Answer

Usually StaleElementReferenceException when element we try to access has appeared but other elements may affect the position of element we are intrested in hence when we try to click or getText or try to do some action on WebElement we get exception which usually says element not attached with DOM.

Solution I tried is as follows:

 protected void clickOnElement(By by) {
        try {
            waitForElementToBeClickableBy(by).click();
        } catch (StaleElementReferenceException e) {
            for (int attempts = 1; attempts < 100; attempts++) {
                try {
                    waitFor(500);
                    logger.info("Stale element found retrying:" + attempts);
                    waitForElementToBeClickableBy(by).click();
                    break;
                } catch (StaleElementReferenceException e1) {
                    logger.info("Stale element found retrying:" + attempts);
                }
            }
        }

protected WebElement waitForElementToBeClickableBy(By by) {
        WebDriverWait wait = new WebDriverWait(getDriver(), 10);
        return wait.until(ExpectedConditions.elementToBeClickable(by));
    }

In above code I first try to wait and then click on element if exception occurs then I catch it and try to loop it as there is a possibility that still all elements may not be loaded and again exception can occur.

score -4 · Accepted Answer

Maybe it was added more recently, but other answers fail to mention Selenium's implicit wait feature, which does all the above for you, and is built into Selenium.

driver.manage().timeouts().implicitlyWait(10,TimeUnit.SECONDS);

This will retry findElement() calls until the element has been found, or for 10 seconds.

Source - http://www.seleniumhq.org/docs/04_webdriver_advanced.jsp

java - 如何避免 Selenium 中的“StaleElementReferenceException”？

16 回答 16

Clean findByAndroidId method that gracefully handles StaleElementReference.

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Reference

Clean `findByAndroidId` method that gracefully handles `StaleElementReference`.