Package 'reactlog'

Reactlog Shiny Module

Description

Displays an iframe of the reactlog in the given application.

Usage

reactlog_module_ui(include_refresh = TRUE, id = "reactlog_module")

reactlog_module_server(
  id = "reactlog_module",
  width = "100%",
  height = 600,
  ...
)

Arguments

include_refresh	should the iframe refresh button be included?
id	shiny module id to use
width, height	HTML attributes to be applied to the reactlog iframe
...	parameters passed to shiny::actionButton()

Details

State will not be preserved between refreshes. To open the reactlog at a particular step, be sure to mark your time points with Cmd+Shift+F3 (Windows: Ctrl+Shift+F3)

See Also

shiny::moduleServer()

Examples

if (!require("shiny")) {
  message("`shiny` required to run example")
  return()
}

library(shiny)
# Enable reactlog
reactlog_enable()

# Define UI for app that draws a histogram ----
ui <- fluidPage(
  tags$h1("Pythagorean theorem"),
  numericInput("a", "A", 3),
  numericInput("b", "B", 4),
  "C:", verbatimTextOutput("c"),
### start ui module
  reactlog_module_ui()
### end ui module
)

server <- function(input, output, session) {
  a2 <- reactive({a <- input$a; req(a); a * a}, label = "a^2")
  b2 <- reactive({b <- input$b; req(b); b * b}, label = "b^2")
  c2 <- reactive({a2() + b2()}, label = "c^2")
  c_val <- reactive({sqrt(c2())}, label = "c")

  output$c <- renderText({
    c_val()
  })

### start server module
  reactlog_module_server()
### end server module

}

if (interactive()) {
  shinyApp(ui = ui, server = server)
}

---

Reactive Log Visualizer

Description

Provides an interactive browser-based tool for visualizing reactive dependencies and execution in your application.

Usage

reactlog_render(log, session_token = NULL, time = TRUE)

reactlog_show(log, time = TRUE, ...)

Arguments

log	Log produced by shiny to be processed
session_token	token to be used to subset which session is displayed. Defaults to all sessions.
time	A boolean that specifies whether or not to display the time that each reactive takes to calculate a result.
...	Future parameter expansion. Currently ignored

Details

To use the reactive log visualizer, start with a fresh R session and run the command reactlog_enable(); then launch your application in the usual way (e.g. using shiny::runApp()). At any time you can hit

Ctrl+F3

(or for Mac users,

Cmd+F3

) in your web browser to launch the reactive log visualization.

The reactive log visualization only includes reactive activity up until the time the report was loaded. If you want to see more recent activity, refresh the browser.

Note that Shiny does not distinguish between reactive dependencies that "belong" to one Shiny user session versus another, so the visualization will include all reactive activity that has taken place in the process, not just for a particular application or session.

As an alternative to pressing

Ctrl/Cmd+F3

–for example, if you are using reactives outside of the context of a Shiny application–you can run the shiny::reactlogShow() function, which will generate the reactive log visualization as a static HTML file and launch it in your default browser. In this case, refreshing your browser will not load new activity into the report; you will need to call shiny::reactlogShow() explicitly.

For security and performance reasons, do not enable the reactlog in production environments. When the option is enabled, it's possible for any user of your app to see at least some of the source code of your reactive expressions and observers.

See Also

shiny::reactlogShow() and reactlog_enable()

Examples

## Not run: 
library(shiny)
library(reactlog)

# tell shiny to log reactivity
reactlog_enable()

# run a shiny app
app <- system.file("examples/01_hello", package = "shiny")
runApp(app)

# once app has closed, display reactlog
shiny::reactlogShow()

## End(Not run)

---

Write reactlog

Description

Write the reactlog to a file. If a session token is provided, all reactive interactions will be subsetted to either the global session or the session provided.

Usage

reactlog_write(log, file = stdout(), session_token = NULL)

Arguments

log	produced by shiny to be written
file	location of output file. If a NULL file is given, the json representation is return.
session_token	Session token identifier to be used when subsetting the complete reactlog

---

Enable or disable the reactlog

Description

Before the reactlog can be visualized, it needs to be enabled. For security and performance reasons, you should not enable the reactlog in a shiny app in production.

Usage

reactlog_enable()

reactlog_disable(warn = TRUE)

Arguments

warn	Should a warning message be shown?

See Also

reactlog_show()

---