Add session$userData feature (#1513)

* Add session$userData

* Tweak wording of NEWS

* Fix broken links

NEWS.md

@@ -15,15 +15,17 @@ shiny 0.14.2.9000
 
 * Added ability through arguments to the `a` tag function called inside `downloadButton()` and `downloadLink()`. Closes [#986](https://github.com/rstudio/shiny/issues/986). ([#1492](https://github.com/rstudio/shiny/pulls/1492))
 
+* Implemented [#1512](https://github.com/rstudio/shiny/issues/1512): added a `userData` environment to `session`, for storing arbitrary session-related variables. Generally, session-scoped variables are created just by declaring normal variables that are local to the Shiny server function, but `session$userData` may be more convenient for some advanced scenarios. ([#1513](https://github.com/rstudio/shiny/pull/1513))
+
 ### Bug fixes
 
-* Fixed [#969](ttps://github.com/rstudio/shiny/issue/969): allow navbarPage's `fluid` param to control both containers. ([#1481](https://github.com/rstudio/shiny/pull/1481))
+* Fixed [#969](https://github.com/rstudio/shiny/issues/969): allow navbarPage's `fluid` param to control both containers. ([#1481](https://github.com/rstudio/shiny/pull/1481))
 
-* Fixed [#1438](https://github.com/rstudio/shiny/issue/1438): `unbindAll()` should not be called when inserting content with `insertUI()` ([#1449](https://github.com/rstudio/shiny/pull/1449))
+* Fixed [#1438](https://github.com/rstudio/shiny/issues/1438): `unbindAll()` should not be called when inserting content with `insertUI()` ([#1449](https://github.com/rstudio/shiny/pull/1449))
 
 * Fixed bug causing `<meta>` tags associated with HTML dependencies of Shiny R Markdown files to be rendered incorrectly. ([#1463](https://github.com/rstudio/shiny/pull/1463))
 
-* Fixed [#1359](https://github.com/rstudio/shiny/issue/1359): `shinyApp()` options argument ignored when passed to `runApp()`. ([#1483](https://github.com/rstudio/shiny/pull/1483))
+* Fixed [#1359](https://github.com/rstudio/shiny/issues/1359): `shinyApp()` options argument ignored when passed to `runApp()`. ([#1483](https://github.com/rstudio/shiny/pull/1483))
 
 shiny 0.14.2
 ============

R/shiny.R

@@ -276,6 +276,10 @@ 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{userData}{
+#'   An environment for app authors and module/package authors to store whatever
+#'   session-specific data they want.
+#' }
 #' \item{resetBrush(brushId)}{
 #'   Resets/clears the brush with the given \code{brushId}, if it exists on
 #'   any \code{imageOutput} or \code{plotOutput} in the app.
@@ -692,6 +696,7 @@ ShinySession <- R6Class(
     closed = logical(0),
     request = 'ANY',      # Websocket request object
     singletons = character(0),  # Tracks singleton HTML fragments sent to the page
+    userData = 'environment',
     user = NULL,
     groups = NULL,
 
@@ -712,6 +717,7 @@ ShinySession <- R6Class(
       self$progressStack <- Stack$new()
       self$files <- Map$new()
       self$downloads <- Map$new()
+      self$userData <- new.env(parent = emptyenv())
 
       self$input <- .createReactiveValues(private$.input, readonly=TRUE)
       .setLabel(self$input, 'input')