Changed customStop to stop(safeError). Refactored some middleware.R code. Fixed downloadHandler's bug of not responding to safeError.

R/conditions.R

@@ -131,8 +131,7 @@ withLogErrors <- function(expr,
     captureStackTraces(expr),
     error = function(cond) {
       # Don't print shiny.silent.error (i.e. validation errors)
-      if (inherits(cond, "shiny.silent.error"))
-        return()
+      if (inherits(cond, "shiny.silent.error")) return()
       if (isTRUE(getOption("show.error.messages"))) {
         printError(cond, full = full, offset = offset)
       }

R/middleware.R

@@ -307,29 +307,19 @@ HandlerManager <- R6Class("HandlerManager",
           }
         },
         call = .httpServer(
-          function(req,
-                   full = getOption("shiny.fullstacktrace", FALSE),
-                   offset = getOption("shiny.stacktraceoffset", TRUE)) {
-
-             withCallingHandlers(captureStackTraces(handlers$invoke(req)),
-               error = function(cond) {
-                 # Don't print shiny.silent.error (i.e. validation errors)
-                 if (inherits(cond, "shiny.silent.error")) return()
-                 if (isTRUE(getOption("show.error.messages"))) {
-                   printError(cond, full = full, offset = offset)
-                   sanitizeErrors = getOption('shiny.sanitize.errors', TRUE)
-
-                   if (inherits(cond, 'shiny.custom.error') || !sanitizeErrors) {
-                     stop(cond$message, call. = FALSE)
-                   }
-                   else {
-                     stop(paste("An error has occurred. Check your logs or",
-                                "contact the app author for clarification."),
-                          call. = FALSE)
-                   }
-                 }
-               }
-             )
+          function (req) {
+            withCallingHandlers(withLogErrors(handlers$invoke(req)),
+              error = function(cond) {
+                sanitizeErrors <- getOption('shiny.sanitize.errors', TRUE)
+                if (inherits(cond, 'shiny.custom.error') || !sanitizeErrors) {
+                  stop(cond$message, call. = FALSE)
+                } else {
+                  stop(paste("An error has occurred. Check your logs or",
+                             "contact the app author for clarification."),
+                       call. = FALSE)
+                }
+              }
+            )
           },
           getOption('shiny.sharedSecret')
         ),

R/shiny.R

@@ -97,11 +97,11 @@ NULL
 #'     of a function appears next to the srcref where it is defined, rather than
 #'     where it is currently being called from.}
 #'   \item{shiny.sanitize.errors}{If \code{TRUE} (the default), then normal
-#'     errors (i.e errors generated by \code{stop}) won't show up in the app; a
-#'     simple generic error message is printed instead (the error and strack trace
+#'     errors (i.e. errors not wrapped in \code{safeError}) won't show up in the app;
+#'     a simple generic error message is printed instead (the error and strack trace
 #'     printed to the console remain unchanged). If you want this behavior in
-#'     general, but you DO want a particular error message to get displayed to the
-#'     user, please use \code{customStop} instead.}
+#'     general, but you DO want a particular error \code{e} to get displayed to the
+#'     user, please use \code{stop(safeError(e))} instead.}
 #' }
 #' @name shiny-options
 NULL
@@ -889,7 +889,7 @@ ShinySession <- R6Class(
         )), silent = TRUE)
         if (inherits(result, 'try-error')) {
           unlink(tmpdata)
-          stop(result)
+          stop(attr(result, "condition", exact = TRUE))
         }
         return(httpResponse(
           200,

R/utils.R

@@ -878,27 +878,29 @@ columnToRowData <- function(data) {
   )
 }
 
-
-#' Create a custom error
+#' Declare an error safe for the user to see
 #'
-#' This should be used when you want to create a custom error to which error
-#' default options do not apply. In particular, \code{customStop} will
+#' This should be used when you want to let the user see an error
+#' message even if the default is to sanitize all errors. If you have an
+#' error \code{e} and call \code{stop(safeError(e))}, then Shiny will
 #' ignore the value of \code{getOption("shiny.sanitize.errors")} and always
 #' display the error in the app itself.
 #'
 #' @param error Either an "error" object or a "character" object (string).
-#' The former will just be rethrown, while the latter will be used as the
-#' message of the error returned by \code{customStop}.
+#' In the latter case, the string will become the message of the error
+#' returned by \code{safeError}.
 #' @param errorClass An optional class to add to the error.
 #'
-#' @details An error generated by \code{customStop} has priority over all
+#' @return An "error" object
+#'
+#' @details An error generated by \code{safeError} has priority over all
 #' other Shiny errors. This can be dangerous. For example, if you have set
 #' \code{options(shiny.sanitize.errors = TRUE)}, then by default all error
 #' messages are omitted in the app, and replaced by a generic error message.
-#' However, this does not apply to \code{customStop}: whatever you pass
+#' However, this does not apply to \code{safeError}: whatever you pass
 #' through \code{error} will be displayed to the user. So, this should only
 #' be used when you are sure that your error message does not contain any
-#' sensitive information. In those situations, \code{customStop} can make
+#' sensitive information. In those situations, \code{safeError} can make
 #' your users' lives much easier by giving them a hint as to where the
 #' error occurred.
 #'
@@ -915,13 +917,13 @@ columnToRowData <- function(data) {
 #' # Define UI
 #' ui <- fluidPage(
 #'   textInput('number', 'Enter your favorite number from 1 to 10', '5'),
-#'   textOutput('errorStop'),
-#'   textOutput('errorCustomStop')
+#'   textOutput('normalError'),
+#'   textOutput('safeError')
 #' )
 #'
 #' # Server logic
 #' server <- function(input, output) {
-#'   output$errorStop <- renderText({
+#'   output$normalError <- renderText({
 #'     number <- input$number
 #'     if (number %in% 1:10) {
 #'       return(paste('You chose', number, '!'))
@@ -931,14 +933,14 @@ columnToRowData <- function(data) {
 #'       )
 #'     }
 #'   })
-#'   output$errorCustomStop <- renderText({
+#'   output$safeError <- renderText({
 #'     number <- input$number
 #'     if (number %in% 1:10) {
 #'       return(paste('You chose', number, '!'))
 #'     } else {
-#'       customStop(
+#'       stop(safeError(
 #'         paste(number, 'is not a number between 1 and 10')
-#'       )
+#'       ))
 #'     }
 #'   })
 #' }
@@ -947,15 +949,21 @@ columnToRowData <- function(data) {
 #' shinyApp(ui, server)
 #' }
 #' @export
-customStop <- function(error, errorClass = character(0)) {
+safeError <- function(error, errorClass = character(0)) {
   if (inherits(error, "error")) {
-    class(error) <- c("shiny.custom.error", errorClass, class(error))
-    stop(error)
+    cond <- structure(
+      list(message = error$message),
+      class = c("shiny.custom.error", errorClass, class(error))
+    )
   } else if (inherits(error, "character")) {
-    stopWithCondition(c("shiny.custom.error", errorClass), error)
+    cond <- structure(
+      list(message = error),
+      class = c("shiny.custom.error", errorClass, "error", "condition")
+    )
   } else {
     stop("The class of the `error` parameter must be either 'error' or 'character'")
   }
+  return(cond)
 }
 
 #' Validate input values and other conditions