Merge pull request #1074 from rstudio/reconnect

Reconnect

R/notifications.R

@@ -3,6 +3,10 @@
 #' These functions show and remove notifications in a Shiny application.
 #'
 #' @param ui Content of message.
+#' @param action Message content that represents an action. For example, this
+#'   could be a link that the user can click on. This is separate from \code{ui}
+#'   so customized layouts can handle the main notification content separately
+#'   from action content.
 #' @param duration Number of seconds to display the message before it
 #'   disappears. Use \code{NULL} to make the message not automatically
 #'   disappear.
@@ -28,7 +32,9 @@
 #'   ),
 #'   server = function(input, output) {
 #'     observeEvent(input$show, {
-#'       showNotification("Message text")
+#'       showNotification("Message text",
+#'         action = a(href = "javascript:location.reload();", "Reload page")
+#'       )
 #'     })
 #'   }
 #' )
@@ -61,8 +67,9 @@
 #' )
 #' }
 #' @export
-showNotification <- function(ui, duration = 5, closeButton = TRUE,
-  id = NULL, type = c("default", "message", "warning", "error"),
+showNotification <- function(ui, action = NULL, duration = 5,
+  closeButton = TRUE, id = NULL,
+  type = c("default", "message", "warning", "error"),
   session = getDefaultReactiveDomain())
 {
 
@@ -70,11 +77,13 @@ showNotification <- function(ui, duration = 5, closeButton = TRUE,
     id <- randomID()
 
   res <- processDeps(ui, session)
+  actionRes <- processDeps(action, session)
 
   session$sendNotification("show",
     list(
       html = res$html,
-      deps = res$deps,
+      action = actionRes$html,
+      deps = c(res$deps, actionRes$deps),
       duration = if (!is.null(duration)) duration * 1000,
       closeButton = closeButton,
       id = id,

R/shiny.R

@@ -241,6 +241,18 @@ workerId <- local({
 #'   This is the request that was used to initiate the websocket connection
 #'   (as opposed to the request that downloaded the web page for the app).
 #' }
+#' \item{allowReconnect(value)}{
+#'   If \code{value} is \code{TRUE} and run in a hosting environment (Shiny
+#'   Server or Connect) with reconnections enabled,  then when the session ends
+#'   due to the network connection closing, the client will attempt to
+#'   reconnect to the server. If a reconnection is successful, the browser will
+#'   send all the current input values to the new session on the server, and
+#'   the server will recalculate any outputs and send them back to the client.
+#'   If \code{value} is \code{FALSE}, reconnections will be disabled (this is
+#'   the default state). If \code{"force"}, then the client browser will always
+#'   attempt to reconnect. The only reason to use \code{"force"} is for testing
+#'   on a local connection (without Shiny Server or Connect).
+#' }
 #' \item{sendCustomMessage(type, message)}{
 #'   Sends a custom message to the web page. \code{type} must be a
 #'   single-element character vector giving the type of message, while
@@ -530,6 +542,14 @@ ShinySession <- R6Class(
     setShowcase = function(value) {
       private$showcase <- !is.null(value) && as.logical(value)
     },
+
+    allowReconnect = function(value) {
+      if (!(identical(value, TRUE) || identical(value, FALSE) || identical(value, "force"))) {
+        stop('value must be TRUE, FALSE, or "force"')
+      }
+      private$write(toJSON(list(allowReconnect = value)))
+    },
+
     defineOutput = function(name, func, label) {
       "Binds an output generating function to this name. The function can either
       take no parameters, or have named parameters for \\code{name} and