處理RSelenium錯誤消息

當前刮取可能具有可變數量的元素的頁面，並且有時還使用不同的選擇器格式化相同的數據元素。目前正試圖忽略RSelenium一些tryCatch代碼引發的錯誤，但是如果指定的元素不是在頁面上仍然停：處理RSelenium錯誤消息

result <- tryCatch({ 
    webElem <- remDr$findElement('xpath', "//tr[(((count(preceding-sibling::*) + 1) = 9) and parent::*)]//span[(((count(preceding-sibling::*) + 1) = 1) and parent::*)]") 
    }, warning = function(cond) { 
    rank1_US <- NA 
    }, 
    error = function(cond) { 
    rank1_US <- NA 
    }, finally = { 
    rank1_US <- webElem$getElementText() %>% unlist(.) %>% ifelse(length(.) == 0, NA, .) 
    })

當特定元素不能在頁面上發現了遇到錯誤：

Selenium message:Unable to locate element: //tr[(((count(preceding-sibling::*) + 1) = 9) and parent::*)]//span[(((count(preceding-sibling::*) + 1) = 1) and parent::*)] 
For documentation on this error, please visit: http://seleniumhq.org/exceptions/no_such_element.html 
Build info: version: '3.0.1', revision: '1969d75', time: '2016-10-18 09:48:19 -0700' 
System info: host: '462a81a34fb2', ip: '172.17.0.2', os.name: 'Linux', os.arch: 'amd64', os.version: '4.4.39-boot2docker', java.version: '1.8.0_111' 
Driver info: org.openqa.selenium.firefox.FirefoxDriver 
Capabilities [{rotatable=false, raisesAccessibilityExceptions=false, firefoxOptions={args=[], profile=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... <truncated> 
Session ID: c7f538b9-b516-411d-ace9-a980353ae442 
*** Element info: {Using=xpath, value=//tr[(((count(preceding-sibling::*) + 1) = 9) and parent::*)]//span[(((count(preceding-sibling::*) + 1) = 1) and parent::*)]}

任何人都有辦法處理錯誤？

來源

2017-01-03 tonyk

，你可以使用類似remDr $ findElement（使用= 「名」，值= 「cityquery」）$ isElementDisplayed（）[[1]] – IndranilGayen

你可以嘗試這樣的：

result <- tryCatch({ 
    suppressMessages({ 
     webElem <- remDr$findElement('xpath', "//tr[(((count(preceding-sibling::*) + 1) = 9) and parent::*)]//span[(((count(preceding-sibling::*) + 1) = 1) and parent::*)]") 
     rank1_US <- webElem$getElementText() %>% unlist(.) %>% ifelse(length(.) == 0, NA, .) 
     rank1_US 
    }) 
    }, 
    error = function(e) { 
    NA_character_ 
    } 
)

來源

2017-01-03 17:59:29 jdharrison

完美地工作，謝謝！ – tonyk

樂意提供幫助。如果你正在使用管道'seleniumPipes'，可能會更適合，而不是'RSelenium' – jdharrison

處理RSelenium錯誤消息

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