feat(R): Add reactlog_read() to read back reactlog_write() output

NAMESPACE

@@ -4,6 +4,7 @@ export(reactlog_disable)
 export(reactlog_enable)
 export(reactlog_module_server)
 export(reactlog_module_ui)
+export(reactlog_read)
 export(reactlog_render)
 export(reactlog_show)
 export(reactlog_write)

NEWS.md

@@ -4,6 +4,8 @@
 
 - The graph legend now shows that a solid line is a dependency, a dashed line is an `isolate()`d dependency, and a dotted line is an inactive dependency (one that existed earlier but is not active at the current step) (#76)
 
+- New `reactlog_read()` reads a file written by `reactlog_write()` back into a log that `reactlog_show()` can display (#71)
+
 - Migrated project license from GPL-3 to the MIT License.
 
 - Added a `?` button to the reactlog header. Hover over it or click it to see every keyboard shortcut, with key names for your operating system. The navigation button tooltips now also use your operating system's key names. The vignette has the same list (#73)

R/showReactLog.R

@@ -76,7 +76,14 @@ reactlog_show <- function(log = shiny::reactlog(), time = TRUE, ...) {
 #'   json representation is return.
 #' @param session_token Session token identifier to be used when subsetting the
 #'   complete reactlog
+#' @seealso [reactlog_read()] to read the file back in.
 #' @export
+#' @examples
+#' \dontrun{
+#' reactlog_write(shiny::reactlog(), "reactlog.json")
+#' log <- reactlog_read("reactlog.json")
+#' reactlog_show(log)
+#' }
 reactlog_write <- function(log, file = stdout(), session_token = NULL) {
   if (!is.null(session_token)) {
     log <- Filter(
@@ -103,6 +110,20 @@ reactlog_write <- function(log, file = stdout(), session_token = NULL) {
   }
 }
 
+#' Read reactlog
+#'
+#' Read a reactlog written by [reactlog_write()], so it can be passed to
+#' [reactlog_show()] or [reactlog_render()].
+#'
+#' @param file JSON file written by [reactlog_write()].
+#' @return The reactlog: a list of log entries with a `version` attribute.
+#' @export
+reactlog_read <- function(file) {
+  log <- jsonlite::read_json(file, simplifyVector = FALSE)
+  # ponytail: the JSON has no version field; "1" is the only version so far
+  attr(log, "version") <- "1"
+  log
+}
 
 write_utf8 <- function(x, file, ...) {
   writeLines(enc2utf8(x), file, ..., useBytes = TRUE)

tests/testthat/test-render.R

@@ -32,3 +32,19 @@ test_that("reactlog_show() defaults to shiny::reactlog()", {
   reactlog_show()
   expect_true(called)
 })
+
+test_that("reactlog_read() reads back what reactlog_write() wrote", {
+  log <- list(list(
+    action = "define", reactId = "r1", label = "a\\b\"c\\",
+    type = "observable", session = NULL, time = 1
+  ))
+  attr(log, "version") <- "1"
+  file <- tempfile(fileext = ".json")
+  on.exit(unlink(file))
+  reactlog_write(log, file)
+
+  log2 <- reactlog_read(file)
+  expect_identical(attr(log2, "version"), "1")
+  expect_identical(reactlog_write(log2, NULL), reactlog_write(log, NULL))
+  expect_no_error(reactlog_render(log2))
+})