rselenium driver error using apply loop

Question

I am using rselenium to automate page navigation in Firefox. My rscript imports a data frame for different conditions and creates a custom function which is then called using the apply command. In the function, each column is referenced through something like this:

#create the function
example <- function(dat) {
    webElem$sendKeysToElement(list(dat[[column1]]))
    #Enters text from the column in the web driver
}
apply(df, 1, example) #Should repeat the function for each row of the data

I have multiple columns that I'm referencing in the apply function so that the data from each one can have a different interaction for the web driver - for example, dat[[column2]], dat[[column3]], and so on. Mostly I'm just sending keys (tabs and arrow keys after findElement(using = 'tag name', 'body') or clicking a button that I find with the findElement function and its id.

I have the script executing and it works fine the first time through, but when it starts over I am getting errors. I would like selenium to open the starting url again, and repeat the navigation using the next line of the data frame. But, what happens is r locks up or reports an error:

Error:   Summary: NoSuchDriver
     Detail: A session is either terminated or not started
     class: org.openqa.selenium.NoSuchSessionException
     Further Details: run errorDetails method

I think that it traces back to the findElements calls in the beginning of the function or the sendKeysToElement call. I have tried closing, quitting, and re-initializing the remote driver but it doesn't seem to make a difference. Are there any tips for troubleshooting? Or a good way to do repeated navigation with selenium in r?

Andrew Jackson · Accepted Answer · 2016-10-29 02:05:17Z

I was able to solve this by recasting my code from an apply function to a for(...) loop. The function I had created was changed minimally.

I started the web driver in the beginning of the loop

remDr <- remoteDriver(extraCapabilities = list(marionette = TRUE))       
remDr$open(silent = TRUE)
remDr$navigate(url)

Throughout the loop I was careful to pass variables to methods relying on rselenium like findElement and sendKeysToElement. That looked something like this:
```
nextBtn(pageBody, remDr)
```
which was shorthand for:
```
nextBtn <- function(element=pageBody, driver=remDr) {
  Sys.sleep(.5)
  driver$findElement(using = 'id',value = "NextButton")$clickElement()
  Sys.sleep(2.5)
}
```
I think that because the methods were called in separate functions, they required being pointed to the right driver elements (even though I had tried to set the default)
And at the end of the for loop, code closed the web driver down:
```
remDr$close()
remDr$quit()
```

The actual call of the loop was

for (i in 1:nrow(df)) {
  surveys(df[i,])
}

The end result is that the loop functions. It opens a new driver instance each time but there weren't errors. References to a specific column were still made with df[[mold0to2]].

Collectives™ on Stack Overflow

rselenium driver error using apply loop

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related