R/testConnection.R

In INWT/dbtools: Tools for Querying Databases

#' Test a connection
#'
#' Test your conncection to local or remote servers. The function will return a
#' logical of length one invisibly with \code{TRUE} for success and \code{FALSE}
#' if any of the connection attempts fail.
#'
#' @param x (Credentials | CredentialsList) a credentials object.
#' @param logger,status (function) a logger function. Has two arguments, first is
#'   \code{x} second is used to indicate success and failure as
#'   \code{logical(1)}.
#' @param ... arguments passed to \link{sendQuery}
#'
#' @examples
#'
#' workingConnection <- Credentials(drv = SQLite, dbname = ":memory:")
#' testConnection(workingConnection)
#'
#' ## To suppress logging:
#' testConnection(workingConnection, loggerSuppress)
#'
#' @export
#' @rdname testConnection
setGeneric("testConnection", function(x, logger = loggerConnection, ...) {
  standardGeneric("testConnection")
})

#' @export
#' @rdname testConnection
setMethod("testConnection", "Credentials", function(x, logger, ...) {

  out <- try(
    silent = TRUE,
    sendQuery(x, "SELECT 1 AS `test`;", ..., errorLogging = function(...) NULL)
  )
  status <- !inherits(out, "try-error")
  logger(x, status)
  invisible(status)

})

#' @export
#' @rdname testConnection
setMethod("testConnection", "CredentialsList", function(x, logger, ...) {
  invisible(all(vapply(x, testConnection, logical(1), logger = logger, ...)))
})

#' @export
#' @rdname testConnection
loggerConnection <- function(x, status) {
  statusString <- if (status) "OK" else "FAILED"
  msgString <- paste(as.character(x), collapse = "--")
  flog.info(paste(msgString, statusString, collapse = " -> "))
}

#' @export
#' @rdname testConnection
loggerSuppress <- function(x, status) {
  invisible(NULL)
}