I am building a function to connect to a specific password-protected ODBC data source that will be used many members of a team - it may be used in multiple environments. In the event that the connection is rejected, I would like to display the warning messages but mask the password that's displayed. If I use suppressWarnings() nothing gets captured as far as I can tell, and if I don't, then the message is displayed in the standard output with the password. Here's the function so far:
connectToData <- function(uid, pswd, dsn='myDSN') {
# Function to connect to myDSN data
#
# Args:
# uid: The user's ID for connecting to the database
# pswd: The user's password for connecting to the database.
# dsn: The DSN for the (already existing) ODBC connection to the 5G
# data. It must be set up on an individual Windows user's machine,
# and they could use any name for it. The default is 'myDSN'
#
# Returns:
# The 'RODBC' class object returned by the RODBC:odbcConnect() function.
#
# TODO: 1) See if you can specify the connection using odbcDriverConnect()
# so as to not rely on user's ODBC connections
# 2) Capture warnings from odbcConnect() and print them while
# disguising password using gsub, as I've attempted to do below.
library('RODBC')
db.conn <- odbcConnect(dsn,
uid=uid,
pwd=pswd)
if(class(db.conn) != 'RODBC') { # Error handling for connections that don't make it
print(gsub(pswd,'******',warnings())) # This doesn't work like I want it to
stop("ODBC connection could not be opened. See warnings()")
} else {
return(db.conn)
}
}
When I run it with the right username/password, I get the right result but when I run it with a bad password, I get this:
> db.conn <- connectTo5G(uid='myID',pswd='badpassword', dsn='myDSN')
[1] "RODBC::odbcDriverConnect(\"DSN=myDSN;UID=myID;PWD=******\")"
[2] "RODBC::odbcDriverConnect(\"DSN=myDSN;UID=myID;PWD=******\")"
Error in connectTo5G(uid = "myID", pswd = "badpassword", dsn = "myDSN") :
ODBC connection could not be opened. See warnings()
In addition: Warning messages:
1: In RODBC::odbcDriverConnect("DSN=myDSN;UID=myID;PWD=badpassword") :
[RODBC] ERROR: state 28000, code 1017, message [Oracle][ODBC][Ora]ORA-01017: invalid username/password; logon denied
2: In RODBC::odbcDriverConnect("DSN=myDSN;UID=myID;PWD=badpassword") :
ODBC connection failed
The print(gsub(...)) appears to work on the most recent warnings from before the function was invoked, and it also only prints the function call that produced the warning, not the text of the warning.
What I would like to do is capture everything after "In addition: Warning messages:" so that I can use gsub() on it, but avoid printing it before the gsub() gets a chance to work on it. I think I need to use withCallingHandlers() but I've looked through the documentation and examples and I cannot figure it out.
Some extra background: This is an Oracle database that locks users out after three attempts to connect so I want to use stop() in case someone writes code that calls this function multiple times. Different users in my group work in both Windows and Linux (sometimes going back and forth) so any solution needs to be flexible.
I do not fully understand what you want to accomplish with ODBC but in terms of converting the error message, you can use tryCatch as @joran suggested
pswd = 'badpassword'
# Just as a reproducable example, a function which fails and outputs badpassword
failing <- function(){
badpassword == 1
}
# This would be the error handling part
tryCatch(failing(),
error = function(e) gsub(pswd, '******', e))
[1] "Error in failing(): object '******' not found\n"
e in this case is the error message and you could think of other ways to manipulate what is put to your screen, so it would not be as easy to guess passwords based on what was replaced. Note for example that 'object' would have been replaced as well if the password had been 'object' for some reason. Or even parts of words, which get replaced as well. At the very least, it would make sense to include word boundaries in the gsub command:
pswd = 'ling'
failing <- function(){
ling == 1
}
tryCatch(failing(),
error = function(e) gsub(paste0("\\b", pswd, "\\b"), '******', e))
[1] "Error in failing(): object '******' not found\n"
For other improvements you should look closely at the specific error messages.
trycatch can also manipulate warning:
pswd = 'ling'
failing <- function(){
warning("ling")
ling == 1
}
tryCatch(failing(),
warning = function(w) gsub(paste0("\\b", pswd, "\\b"), '******', w),
error = function(e) gsub(paste0("\\b", pswd, "\\b"), '******', e))
[1] "simpleWarning in failing(): ******\n"
This will not show the error then, however.
If you really want to catch all output from errors and warnings, you do indeed need withCallingHandlers, which works mostly in the same way, except that it does not terminate the rest of the evaluation.
pswd = 'ling'
failing <- function(pswd){
warning(pswd)
warning("asd")
stop(pswd)
}
withCallingHandlers(failing(),
warning = function(w) {
w <- gsub(paste0("\\b", pswd, "\\b"), '******', w)
warning(w)},
error = function(e){
e <- gsub(paste0("\\b", pswd, "\\b"), '******', e)
stop(e)
})