TryCatch in R - loop webscraping

Question

I'm using RSelenium to trying to webscrape several URLs to extract information about price over the years. My problem is that some of the URLs may not exist (I generated the URLs with the years that I need the information) and I need to skip it and go to the next URL without stop.

I think that tryCatch() would help but I don't know exactly how to use it:

base = "https://www.cochrane.org"
codes_test = list("03040300")
month_ = c("01", "02", "03", "04","05","06","07","08", "09", "10", "11","12")
year_ = c(2008:2019)
html <- apply(expand.grid(base, codes_test, month_, year_), 
              MARGIN = 1, 
              FUN = function(x)paste(x, collapse = "/"))


remDr$navigate("https://www.cochrane.org/0304070017/10/2017")
webElement <- remDr$findElement(value = '//*[@id="acessoAutomatico"]/a')
webElement$clickElement() 

l <-length(html) 

for(j in seq(html)){ 
  sigtap <- foreach(i=1:l) %dopar% {

    tryCatch(stop("no"), error = function(e) cat("Error: ",e$message, "\n")) 
    remDr$navigate(html[i])

    names <- remDr$findElements(value = ' //*[@id="content"]/fieldset[4]/fieldset/table/tbody/tr[2]/td[1]/label | //*[@id="content"]/fieldset[4]/fieldset/table/tbody/tr[1]/td[3]/label | //*[@id="content"]/fieldset[4]/fieldset/table/tbody/tr[2]/td[3]/label | //*[@id="content"]/fieldset[4]/fieldset/table/tbody/tr[3]/td[3]/label ' )

    infos <- remDr$findElements(value = '[@id="valorSA_Total"] | //*[@id="valorSH"] | //*[@id="valorSP"] | //*[@id="totalInternacao"]')

  identificadores <- unlist(lapply(names, function(x) {x$getElementText()}))
  informacoes <- unlist(lapply(infos, function(x) {x$getElementText()}))
  bind_test[[i]] <- data.frame(identificadores , informacoes)

      }}

write.csv(bind_test[[i]], file = paste(bind_test, '.csv', sep = '_'))

Thank you all for any help!

Answer 1

Assuming that the remDr$navigate(html[i]) is what will throw the error you seek to catch, try as follows:

 success <- tryCatch({
   remDr$navigate(html[i])
   TRUE
   }, 
   warning = function(w) { FALSE },
   error = function(e) { FALSE },
   finally = { })

if (!success) next