RSelenium 抛出 StaleElementReference 错误

Question

我正在尝试使用 RSelenium 抓取此网站 link。我已经成功地抓取了页面上的大部分内容，但试图打通“设施访问”和“设施投诉”。由于这两个按钮在我使用开发人员工具检查它们时都有一个 javascript href，因此我一直在使用 phantomjs 和 RSelenium。

我可以通过 phantom 成功导航到该页面，但是每当我尝试使用 $getElementText 从字段中提取文本时，都会抛出以下错误：

Selenium message:{"errorMessage":"Element does not exist in cache","request":{"headers":{"Accept":"application/json, text/xml, application/xml, */*","Accept-Encoding":"gzip, deflate","Host":"localhost:4444","User-Agent":"libcurl/7.53.1 r-curl/2.6 httr/1.2.1"},"httpVersion":"1.1","method":"GET","url":"/attribute/id","urlParsed":{"anchor":"","query":"","file":"id","directory":"/attribute/","path":"/attribute/id","relative":"/attribute/id","port":"","host":"","password":"","user":"","userInfo":"","authority":"","protocol":"","source":"/attribute/id","queryKey":{},"chunks":["attribute","id"]},"urlOriginal":"/session/c0f30500-55d0-11e7-96dd-3b147ee40d88/element/:wdc:1497974074536/attribute/id"}}

 Show Traceback
Error: Summary: StaleElementReference Detail: An element command failed because the referenced element is no longer attached to the DOM. class: org.openqa.selenium.StaleElementReferenceException Further Details: run errorDetails method

当我使用 $currentURL 和 $screenship(display = T) 时，它会显示正确的网站和正确的链接。

我知道这与元素如何附加到 DOM 有关，但我不确定如何解决 R 中的问题

代码如下：

url <- "https://dhs.arkansas.gov/dccece/cclas/FacilityInformation.aspx?FacilityNumber=23516"
rd<-remoteDriver(browserName = 'phantomjs')

rd$open()

rd$navigate(url)

webElem<- rd$findElement(using="xpath", value = '//*[@id="ctl00_ContentPlaceHolder1_lbtnVisits"]')

webElem$clickElement()

webElem$findElements('css',"#aspnetForm > div.page > div.main")

webElem$getElementAttribute("id")

Answer 1

点击webElem，您可能会收到StaleElementReference。

webElem 元素在点击后很可能在 DOM 中被修改，因此如果您再次尝试“使用”webElem，它不再附加到 DOM 并被视为“陈旧”。

---

一个简单的解决方法是在单击 webElem 后重新定位它：

webElem <- rd$findElement(...
webElem$clickElement()
webElem <- rd$findElement(... # re-locate webElem
webElem$findElements('css',"#aspnetForm > div.page > div.main")